Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
Uwe Zeisberger | f30c226 | 2006-10-03 23:01:26 +0200 | [diff] [blame] | 2 | * mm/page-writeback.c |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3 | * |
| 4 | * Copyright (C) 2002, Linus Torvalds. |
Peter Zijlstra | 90eec10 | 2015-11-16 11:08:45 +0100 | [diff] [blame] | 5 | * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 6 | * |
| 7 | * Contains functions related to writing back dirty pages at the |
| 8 | * address_space level. |
| 9 | * |
Francois Cami | e1f8e87 | 2008-10-15 22:01:59 -0700 | [diff] [blame] | 10 | * 10Apr2002 Andrew Morton |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 11 | * Initial version |
| 12 | */ |
| 13 | |
| 14 | #include <linux/kernel.h> |
Paul Gortmaker | b95f1b31 | 2011-10-16 02:01:52 -0400 | [diff] [blame] | 15 | #include <linux/export.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 16 | #include <linux/spinlock.h> |
| 17 | #include <linux/fs.h> |
| 18 | #include <linux/mm.h> |
| 19 | #include <linux/swap.h> |
| 20 | #include <linux/slab.h> |
| 21 | #include <linux/pagemap.h> |
| 22 | #include <linux/writeback.h> |
| 23 | #include <linux/init.h> |
| 24 | #include <linux/backing-dev.h> |
Andrew Morton | 55e829a | 2006-12-10 02:19:27 -0800 | [diff] [blame] | 25 | #include <linux/task_io_accounting_ops.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 26 | #include <linux/blkdev.h> |
| 27 | #include <linux/mpage.h> |
Peter Zijlstra | d08b385 | 2006-09-25 23:30:57 -0700 | [diff] [blame] | 28 | #include <linux/rmap.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 29 | #include <linux/percpu.h> |
| 30 | #include <linux/notifier.h> |
| 31 | #include <linux/smp.h> |
| 32 | #include <linux/sysctl.h> |
| 33 | #include <linux/cpu.h> |
| 34 | #include <linux/syscalls.h> |
Al Viro | ff01bb4 | 2011-09-16 02:31:11 -0400 | [diff] [blame] | 35 | #include <linux/buffer_head.h> /* __set_page_dirty_buffers */ |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 36 | #include <linux/pagevec.h> |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 37 | #include <linux/timer.h> |
Clark Williams | 8bd75c7 | 2013-02-07 09:47:07 -0600 | [diff] [blame] | 38 | #include <linux/sched/rt.h> |
Ingo Molnar | f361bf4 | 2017-02-03 23:47:37 +0100 | [diff] [blame] | 39 | #include <linux/sched/signal.h> |
Lisa Du | 6e543d5 | 2013-09-11 14:22:36 -0700 | [diff] [blame] | 40 | #include <linux/mm_inline.h> |
Dave Chinner | 028c2dd | 2010-07-07 13:24:07 +1000 | [diff] [blame] | 41 | #include <trace/events/writeback.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 42 | |
Lisa Du | 6e543d5 | 2013-09-11 14:22:36 -0700 | [diff] [blame] | 43 | #include "internal.h" |
| 44 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 45 | /* |
Wu Fengguang | ffd1f60 | 2011-06-19 22:18:42 -0600 | [diff] [blame] | 46 | * Sleep at most 200ms at a time in balance_dirty_pages(). |
| 47 | */ |
| 48 | #define MAX_PAUSE max(HZ/5, 1) |
| 49 | |
| 50 | /* |
Wu Fengguang | 5b9b357 | 2011-12-06 13:17:17 -0600 | [diff] [blame] | 51 | * Try to keep balance_dirty_pages() call intervals higher than this many pages |
| 52 | * by raising pause time to max_pause when falls below it. |
| 53 | */ |
| 54 | #define DIRTY_POLL_THRESH (128 >> (PAGE_SHIFT - 10)) |
| 55 | |
| 56 | /* |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 57 | * Estimate write bandwidth at 200ms intervals. |
| 58 | */ |
| 59 | #define BANDWIDTH_INTERVAL max(HZ/5, 1) |
| 60 | |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 61 | #define RATELIMIT_CALC_SHIFT 10 |
| 62 | |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 63 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 64 | * After a CPU has dirtied this many pages, balance_dirty_pages_ratelimited |
| 65 | * will look to see if it needs to force writeback or throttling. |
| 66 | */ |
| 67 | static long ratelimit_pages = 32; |
| 68 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 69 | /* The following parameters are exported via /proc/sys/vm */ |
| 70 | |
| 71 | /* |
Jens Axboe | 5b0830c | 2009-09-23 19:37:09 +0200 | [diff] [blame] | 72 | * Start background writeback (via writeback threads) at this percentage |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 73 | */ |
Wu Fengguang | 1b5e62b | 2009-03-23 08:57:38 +0800 | [diff] [blame] | 74 | int dirty_background_ratio = 10; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 75 | |
| 76 | /* |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 77 | * dirty_background_bytes starts at 0 (disabled) so that it is a function of |
| 78 | * dirty_background_ratio * the amount of dirtyable memory |
| 79 | */ |
| 80 | unsigned long dirty_background_bytes; |
| 81 | |
| 82 | /* |
Bron Gondwana | 195cf453 | 2008-02-04 22:29:20 -0800 | [diff] [blame] | 83 | * free highmem will not be subtracted from the total free memory |
| 84 | * for calculating free ratios if vm_highmem_is_dirtyable is true |
| 85 | */ |
| 86 | int vm_highmem_is_dirtyable; |
| 87 | |
| 88 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 89 | * The generator of dirty data starts writeback at this percentage |
| 90 | */ |
Wu Fengguang | 1b5e62b | 2009-03-23 08:57:38 +0800 | [diff] [blame] | 91 | int vm_dirty_ratio = 20; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 92 | |
| 93 | /* |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 94 | * vm_dirty_bytes starts at 0 (disabled) so that it is a function of |
| 95 | * vm_dirty_ratio * the amount of dirtyable memory |
| 96 | */ |
| 97 | unsigned long vm_dirty_bytes; |
| 98 | |
| 99 | /* |
Alexey Dobriyan | 704503d | 2009-03-31 15:23:18 -0700 | [diff] [blame] | 100 | * The interval between `kupdate'-style writebacks |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 101 | */ |
Toshiyuki Okajima | 22ef37e | 2009-05-16 22:56:28 -0700 | [diff] [blame] | 102 | unsigned int dirty_writeback_interval = 5 * 100; /* centiseconds */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 103 | |
Artem Bityutskiy | 91913a2 | 2012-03-21 22:33:00 -0400 | [diff] [blame] | 104 | EXPORT_SYMBOL_GPL(dirty_writeback_interval); |
| 105 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 106 | /* |
Alexey Dobriyan | 704503d | 2009-03-31 15:23:18 -0700 | [diff] [blame] | 107 | * The longest time for which data is allowed to remain dirty |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 108 | */ |
Toshiyuki Okajima | 22ef37e | 2009-05-16 22:56:28 -0700 | [diff] [blame] | 109 | unsigned int dirty_expire_interval = 30 * 100; /* centiseconds */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 110 | |
| 111 | /* |
| 112 | * Flag that makes the machine dump writes/reads and block dirtyings. |
| 113 | */ |
| 114 | int block_dump; |
| 115 | |
| 116 | /* |
Bart Samwel | ed5b43f | 2006-03-24 03:15:49 -0800 | [diff] [blame] | 117 | * Flag that puts the machine in "laptop mode". Doubles as a timeout in jiffies: |
| 118 | * a full sync is triggered after this time elapses without any disk activity. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 119 | */ |
| 120 | int laptop_mode; |
| 121 | |
| 122 | EXPORT_SYMBOL(laptop_mode); |
| 123 | |
| 124 | /* End of sysctl-exported parameters */ |
| 125 | |
Tejun Heo | dcc25ae | 2015-05-22 18:23:22 -0400 | [diff] [blame] | 126 | struct wb_domain global_wb_domain; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 127 | |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 128 | /* consolidated parameters for balance_dirty_pages() and its subroutines */ |
| 129 | struct dirty_throttle_control { |
Tejun Heo | e9f07df | 2015-05-22 18:23:28 -0400 | [diff] [blame] | 130 | #ifdef CONFIG_CGROUP_WRITEBACK |
| 131 | struct wb_domain *dom; |
Tejun Heo | 9fc3a43 | 2015-05-22 18:23:30 -0400 | [diff] [blame] | 132 | struct dirty_throttle_control *gdtc; /* only set in memcg dtc's */ |
Tejun Heo | e9f07df | 2015-05-22 18:23:28 -0400 | [diff] [blame] | 133 | #endif |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 134 | struct bdi_writeback *wb; |
Tejun Heo | e9770b3 | 2015-05-22 18:23:27 -0400 | [diff] [blame] | 135 | struct fprop_local_percpu *wb_completions; |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 136 | |
Tejun Heo | 9fc3a43 | 2015-05-22 18:23:30 -0400 | [diff] [blame] | 137 | unsigned long avail; /* dirtyable */ |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 138 | unsigned long dirty; /* file_dirty + write + nfs */ |
| 139 | unsigned long thresh; /* dirty threshold */ |
| 140 | unsigned long bg_thresh; /* dirty background threshold */ |
| 141 | |
| 142 | unsigned long wb_dirty; /* per-wb counterparts */ |
| 143 | unsigned long wb_thresh; |
Tejun Heo | 970fb01 | 2015-05-22 18:23:24 -0400 | [diff] [blame] | 144 | unsigned long wb_bg_thresh; |
Tejun Heo | daddfa3 | 2015-05-22 18:23:26 -0400 | [diff] [blame] | 145 | |
| 146 | unsigned long pos_ratio; |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 147 | }; |
| 148 | |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 149 | /* |
| 150 | * Length of period for aging writeout fractions of bdis. This is an |
| 151 | * arbitrarily chosen number. The longer the period, the slower fractions will |
| 152 | * reflect changes in current writeout rate. |
| 153 | */ |
| 154 | #define VM_COMPLETIONS_PERIOD_LEN (3*HZ) |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 155 | |
Tejun Heo | 693108a | 2015-05-22 17:13:49 -0400 | [diff] [blame] | 156 | #ifdef CONFIG_CGROUP_WRITEBACK |
| 157 | |
Tejun Heo | d60d1bd | 2015-09-29 12:47:53 -0400 | [diff] [blame] | 158 | #define GDTC_INIT(__wb) .wb = (__wb), \ |
| 159 | .dom = &global_wb_domain, \ |
| 160 | .wb_completions = &(__wb)->completions |
| 161 | |
Tejun Heo | 9fc3a43 | 2015-05-22 18:23:30 -0400 | [diff] [blame] | 162 | #define GDTC_INIT_NO_WB .dom = &global_wb_domain |
Tejun Heo | d60d1bd | 2015-09-29 12:47:53 -0400 | [diff] [blame] | 163 | |
| 164 | #define MDTC_INIT(__wb, __gdtc) .wb = (__wb), \ |
| 165 | .dom = mem_cgroup_wb_domain(__wb), \ |
| 166 | .wb_completions = &(__wb)->memcg_completions, \ |
| 167 | .gdtc = __gdtc |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 168 | |
| 169 | static bool mdtc_valid(struct dirty_throttle_control *dtc) |
| 170 | { |
| 171 | return dtc->dom; |
| 172 | } |
Tejun Heo | e9f07df | 2015-05-22 18:23:28 -0400 | [diff] [blame] | 173 | |
| 174 | static struct wb_domain *dtc_dom(struct dirty_throttle_control *dtc) |
| 175 | { |
| 176 | return dtc->dom; |
| 177 | } |
| 178 | |
Tejun Heo | 9fc3a43 | 2015-05-22 18:23:30 -0400 | [diff] [blame] | 179 | static struct dirty_throttle_control *mdtc_gdtc(struct dirty_throttle_control *mdtc) |
| 180 | { |
| 181 | return mdtc->gdtc; |
| 182 | } |
| 183 | |
Tejun Heo | 841710a | 2015-05-22 18:23:33 -0400 | [diff] [blame] | 184 | static struct fprop_local_percpu *wb_memcg_completions(struct bdi_writeback *wb) |
| 185 | { |
| 186 | return &wb->memcg_completions; |
| 187 | } |
| 188 | |
Tejun Heo | 693108a | 2015-05-22 17:13:49 -0400 | [diff] [blame] | 189 | static void wb_min_max_ratio(struct bdi_writeback *wb, |
| 190 | unsigned long *minp, unsigned long *maxp) |
| 191 | { |
| 192 | unsigned long this_bw = wb->avg_write_bandwidth; |
| 193 | unsigned long tot_bw = atomic_long_read(&wb->bdi->tot_write_bandwidth); |
| 194 | unsigned long long min = wb->bdi->min_ratio; |
| 195 | unsigned long long max = wb->bdi->max_ratio; |
| 196 | |
| 197 | /* |
| 198 | * @wb may already be clean by the time control reaches here and |
| 199 | * the total may not include its bw. |
| 200 | */ |
| 201 | if (this_bw < tot_bw) { |
| 202 | if (min) { |
| 203 | min *= this_bw; |
| 204 | do_div(min, tot_bw); |
| 205 | } |
| 206 | if (max < 100) { |
| 207 | max *= this_bw; |
| 208 | do_div(max, tot_bw); |
| 209 | } |
| 210 | } |
| 211 | |
| 212 | *minp = min; |
| 213 | *maxp = max; |
| 214 | } |
| 215 | |
| 216 | #else /* CONFIG_CGROUP_WRITEBACK */ |
| 217 | |
Tejun Heo | d60d1bd | 2015-09-29 12:47:53 -0400 | [diff] [blame] | 218 | #define GDTC_INIT(__wb) .wb = (__wb), \ |
| 219 | .wb_completions = &(__wb)->completions |
Tejun Heo | 9fc3a43 | 2015-05-22 18:23:30 -0400 | [diff] [blame] | 220 | #define GDTC_INIT_NO_WB |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 221 | #define MDTC_INIT(__wb, __gdtc) |
| 222 | |
| 223 | static bool mdtc_valid(struct dirty_throttle_control *dtc) |
| 224 | { |
| 225 | return false; |
| 226 | } |
Tejun Heo | e9f07df | 2015-05-22 18:23:28 -0400 | [diff] [blame] | 227 | |
| 228 | static struct wb_domain *dtc_dom(struct dirty_throttle_control *dtc) |
| 229 | { |
| 230 | return &global_wb_domain; |
| 231 | } |
| 232 | |
Tejun Heo | 9fc3a43 | 2015-05-22 18:23:30 -0400 | [diff] [blame] | 233 | static struct dirty_throttle_control *mdtc_gdtc(struct dirty_throttle_control *mdtc) |
| 234 | { |
| 235 | return NULL; |
| 236 | } |
| 237 | |
Tejun Heo | 841710a | 2015-05-22 18:23:33 -0400 | [diff] [blame] | 238 | static struct fprop_local_percpu *wb_memcg_completions(struct bdi_writeback *wb) |
| 239 | { |
| 240 | return NULL; |
| 241 | } |
| 242 | |
Tejun Heo | 693108a | 2015-05-22 17:13:49 -0400 | [diff] [blame] | 243 | static void wb_min_max_ratio(struct bdi_writeback *wb, |
| 244 | unsigned long *minp, unsigned long *maxp) |
| 245 | { |
| 246 | *minp = wb->bdi->min_ratio; |
| 247 | *maxp = wb->bdi->max_ratio; |
| 248 | } |
| 249 | |
| 250 | #endif /* CONFIG_CGROUP_WRITEBACK */ |
| 251 | |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 252 | /* |
Johannes Weiner | a756cf5 | 2012-01-10 15:07:49 -0800 | [diff] [blame] | 253 | * In a memory zone, there is a certain amount of pages we consider |
| 254 | * available for the page cache, which is essentially the number of |
| 255 | * free and reclaimable pages, minus some zone reserves to protect |
| 256 | * lowmem and the ability to uphold the zone's watermarks without |
| 257 | * requiring writeback. |
| 258 | * |
| 259 | * This number of dirtyable pages is the base value of which the |
| 260 | * user-configurable dirty ratio is the effictive number of pages that |
| 261 | * are allowed to be actually dirtied. Per individual zone, or |
| 262 | * globally by using the sum of dirtyable pages over all zones. |
| 263 | * |
| 264 | * Because the user is allowed to specify the dirty limit globally as |
| 265 | * absolute number of bytes, calculating the per-zone dirty limit can |
| 266 | * require translating the configured limit into a percentage of |
| 267 | * global dirtyable memory first. |
| 268 | */ |
| 269 | |
Johannes Weiner | a804552 | 2014-01-29 14:05:39 -0800 | [diff] [blame] | 270 | /** |
Mel Gorman | 281e372 | 2016-07-28 15:46:11 -0700 | [diff] [blame] | 271 | * node_dirtyable_memory - number of dirtyable pages in a node |
| 272 | * @pgdat: the node |
Johannes Weiner | a804552 | 2014-01-29 14:05:39 -0800 | [diff] [blame] | 273 | * |
Mel Gorman | 281e372 | 2016-07-28 15:46:11 -0700 | [diff] [blame] | 274 | * Returns the node's number of pages potentially available for dirty |
| 275 | * page cache. This is the base value for the per-node dirty limits. |
Johannes Weiner | a804552 | 2014-01-29 14:05:39 -0800 | [diff] [blame] | 276 | */ |
Mel Gorman | 281e372 | 2016-07-28 15:46:11 -0700 | [diff] [blame] | 277 | static unsigned long node_dirtyable_memory(struct pglist_data *pgdat) |
Johannes Weiner | a804552 | 2014-01-29 14:05:39 -0800 | [diff] [blame] | 278 | { |
Mel Gorman | 281e372 | 2016-07-28 15:46:11 -0700 | [diff] [blame] | 279 | unsigned long nr_pages = 0; |
| 280 | int z; |
Johannes Weiner | a804552 | 2014-01-29 14:05:39 -0800 | [diff] [blame] | 281 | |
Mel Gorman | 281e372 | 2016-07-28 15:46:11 -0700 | [diff] [blame] | 282 | for (z = 0; z < MAX_NR_ZONES; z++) { |
| 283 | struct zone *zone = pgdat->node_zones + z; |
| 284 | |
| 285 | if (!populated_zone(zone)) |
| 286 | continue; |
| 287 | |
| 288 | nr_pages += zone_page_state(zone, NR_FREE_PAGES); |
| 289 | } |
| 290 | |
Johannes Weiner | a8d0143 | 2016-01-14 15:20:15 -0800 | [diff] [blame] | 291 | /* |
| 292 | * Pages reserved for the kernel should not be considered |
| 293 | * dirtyable, to prevent a situation where reclaim has to |
| 294 | * clean pages in order to balance the zones. |
| 295 | */ |
Mel Gorman | 281e372 | 2016-07-28 15:46:11 -0700 | [diff] [blame] | 296 | nr_pages -= min(nr_pages, pgdat->totalreserve_pages); |
Johannes Weiner | a804552 | 2014-01-29 14:05:39 -0800 | [diff] [blame] | 297 | |
Mel Gorman | 281e372 | 2016-07-28 15:46:11 -0700 | [diff] [blame] | 298 | nr_pages += node_page_state(pgdat, NR_INACTIVE_FILE); |
| 299 | nr_pages += node_page_state(pgdat, NR_ACTIVE_FILE); |
Johannes Weiner | a804552 | 2014-01-29 14:05:39 -0800 | [diff] [blame] | 300 | |
| 301 | return nr_pages; |
| 302 | } |
| 303 | |
Johannes Weiner | 1edf223 | 2012-01-10 15:06:57 -0800 | [diff] [blame] | 304 | static unsigned long highmem_dirtyable_memory(unsigned long total) |
| 305 | { |
| 306 | #ifdef CONFIG_HIGHMEM |
| 307 | int node; |
Mel Gorman | bb4cc2b | 2016-07-28 15:47:29 -0700 | [diff] [blame] | 308 | unsigned long x = 0; |
Joonsoo Kim | 09b4ab3 | 2016-05-19 17:12:20 -0700 | [diff] [blame] | 309 | int i; |
Johannes Weiner | 1edf223 | 2012-01-10 15:06:57 -0800 | [diff] [blame] | 310 | |
| 311 | for_each_node_state(node, N_HIGH_MEMORY) { |
Mel Gorman | 281e372 | 2016-07-28 15:46:11 -0700 | [diff] [blame] | 312 | for (i = ZONE_NORMAL + 1; i < MAX_NR_ZONES; i++) { |
| 313 | struct zone *z; |
Minchan Kim | 9cb937e | 2016-07-28 15:47:08 -0700 | [diff] [blame] | 314 | unsigned long nr_pages; |
Johannes Weiner | 1edf223 | 2012-01-10 15:06:57 -0800 | [diff] [blame] | 315 | |
Mel Gorman | 281e372 | 2016-07-28 15:46:11 -0700 | [diff] [blame] | 316 | if (!is_highmem_idx(i)) |
| 317 | continue; |
| 318 | |
| 319 | z = &NODE_DATA(node)->node_zones[i]; |
Minchan Kim | 9cb937e | 2016-07-28 15:47:08 -0700 | [diff] [blame] | 320 | if (!populated_zone(z)) |
| 321 | continue; |
Mel Gorman | 281e372 | 2016-07-28 15:46:11 -0700 | [diff] [blame] | 322 | |
Minchan Kim | 9cb937e | 2016-07-28 15:47:08 -0700 | [diff] [blame] | 323 | nr_pages = zone_page_state(z, NR_FREE_PAGES); |
Mel Gorman | 281e372 | 2016-07-28 15:46:11 -0700 | [diff] [blame] | 324 | /* watch for underflows */ |
Minchan Kim | 9cb937e | 2016-07-28 15:47:08 -0700 | [diff] [blame] | 325 | nr_pages -= min(nr_pages, high_wmark_pages(z)); |
Mel Gorman | bb4cc2b | 2016-07-28 15:47:29 -0700 | [diff] [blame] | 326 | nr_pages += zone_page_state(z, NR_ZONE_INACTIVE_FILE); |
| 327 | nr_pages += zone_page_state(z, NR_ZONE_ACTIVE_FILE); |
| 328 | x += nr_pages; |
Joonsoo Kim | 09b4ab3 | 2016-05-19 17:12:20 -0700 | [diff] [blame] | 329 | } |
Johannes Weiner | 1edf223 | 2012-01-10 15:06:57 -0800 | [diff] [blame] | 330 | } |
Mel Gorman | 281e372 | 2016-07-28 15:46:11 -0700 | [diff] [blame] | 331 | |
Johannes Weiner | 1edf223 | 2012-01-10 15:06:57 -0800 | [diff] [blame] | 332 | /* |
Sonny Rao | c8b74c2f | 2012-12-20 15:05:07 -0800 | [diff] [blame] | 333 | * Unreclaimable memory (kernel memory or anonymous memory |
| 334 | * without swap) can bring down the dirtyable pages below |
| 335 | * the zone's dirty balance reserve and the above calculation |
| 336 | * will underflow. However we still want to add in nodes |
| 337 | * which are below threshold (negative values) to get a more |
| 338 | * accurate calculation but make sure that the total never |
| 339 | * underflows. |
| 340 | */ |
| 341 | if ((long)x < 0) |
| 342 | x = 0; |
| 343 | |
| 344 | /* |
Johannes Weiner | 1edf223 | 2012-01-10 15:06:57 -0800 | [diff] [blame] | 345 | * Make sure that the number of highmem pages is never larger |
| 346 | * than the number of the total dirtyable memory. This can only |
| 347 | * occur in very strange VM situations but we want to make sure |
| 348 | * that this does not occur. |
| 349 | */ |
| 350 | return min(x, total); |
| 351 | #else |
| 352 | return 0; |
| 353 | #endif |
| 354 | } |
| 355 | |
| 356 | /** |
Johannes Weiner | ccafa28 | 2012-01-10 15:07:44 -0800 | [diff] [blame] | 357 | * global_dirtyable_memory - number of globally dirtyable pages |
Johannes Weiner | 1edf223 | 2012-01-10 15:06:57 -0800 | [diff] [blame] | 358 | * |
Johannes Weiner | ccafa28 | 2012-01-10 15:07:44 -0800 | [diff] [blame] | 359 | * Returns the global number of pages potentially available for dirty |
| 360 | * page cache. This is the base value for the global dirty limits. |
Johannes Weiner | 1edf223 | 2012-01-10 15:06:57 -0800 | [diff] [blame] | 361 | */ |
H Hartley Sweeten | 18cf8cf | 2012-04-12 13:44:20 -0700 | [diff] [blame] | 362 | static unsigned long global_dirtyable_memory(void) |
Johannes Weiner | 1edf223 | 2012-01-10 15:06:57 -0800 | [diff] [blame] | 363 | { |
| 364 | unsigned long x; |
| 365 | |
Michal Hocko | c41f012 | 2017-09-06 16:23:36 -0700 | [diff] [blame] | 366 | x = global_zone_page_state(NR_FREE_PAGES); |
Johannes Weiner | a8d0143 | 2016-01-14 15:20:15 -0800 | [diff] [blame] | 367 | /* |
| 368 | * Pages reserved for the kernel should not be considered |
| 369 | * dirtyable, to prevent a situation where reclaim has to |
| 370 | * clean pages in order to balance the zones. |
| 371 | */ |
| 372 | x -= min(x, totalreserve_pages); |
Johannes Weiner | 1edf223 | 2012-01-10 15:06:57 -0800 | [diff] [blame] | 373 | |
Mel Gorman | 599d0c9 | 2016-07-28 15:45:31 -0700 | [diff] [blame] | 374 | x += global_node_page_state(NR_INACTIVE_FILE); |
| 375 | x += global_node_page_state(NR_ACTIVE_FILE); |
Johannes Weiner | a804552 | 2014-01-29 14:05:39 -0800 | [diff] [blame] | 376 | |
Johannes Weiner | 1edf223 | 2012-01-10 15:06:57 -0800 | [diff] [blame] | 377 | if (!vm_highmem_is_dirtyable) |
| 378 | x -= highmem_dirtyable_memory(x); |
| 379 | |
| 380 | return x + 1; /* Ensure that we never return 0 */ |
| 381 | } |
| 382 | |
Tejun Heo | 9fc3a43 | 2015-05-22 18:23:30 -0400 | [diff] [blame] | 383 | /** |
| 384 | * domain_dirty_limits - calculate thresh and bg_thresh for a wb_domain |
| 385 | * @dtc: dirty_throttle_control of interest |
Johannes Weiner | ccafa28 | 2012-01-10 15:07:44 -0800 | [diff] [blame] | 386 | * |
Tejun Heo | 9fc3a43 | 2015-05-22 18:23:30 -0400 | [diff] [blame] | 387 | * Calculate @dtc->thresh and ->bg_thresh considering |
| 388 | * vm_dirty_{bytes|ratio} and dirty_background_{bytes|ratio}. The caller |
| 389 | * must ensure that @dtc->avail is set before calling this function. The |
| 390 | * dirty limits will be lifted by 1/4 for PF_LESS_THROTTLE (ie. nfsd) and |
Johannes Weiner | ccafa28 | 2012-01-10 15:07:44 -0800 | [diff] [blame] | 391 | * real-time tasks. |
| 392 | */ |
Tejun Heo | 9fc3a43 | 2015-05-22 18:23:30 -0400 | [diff] [blame] | 393 | static void domain_dirty_limits(struct dirty_throttle_control *dtc) |
| 394 | { |
| 395 | const unsigned long available_memory = dtc->avail; |
| 396 | struct dirty_throttle_control *gdtc = mdtc_gdtc(dtc); |
| 397 | unsigned long bytes = vm_dirty_bytes; |
| 398 | unsigned long bg_bytes = dirty_background_bytes; |
Tejun Heo | 62a584f | 2016-05-27 14:34:46 -0400 | [diff] [blame] | 399 | /* convert ratios to per-PAGE_SIZE for higher precision */ |
| 400 | unsigned long ratio = (vm_dirty_ratio * PAGE_SIZE) / 100; |
| 401 | unsigned long bg_ratio = (dirty_background_ratio * PAGE_SIZE) / 100; |
Tejun Heo | 9fc3a43 | 2015-05-22 18:23:30 -0400 | [diff] [blame] | 402 | unsigned long thresh; |
| 403 | unsigned long bg_thresh; |
| 404 | struct task_struct *tsk; |
| 405 | |
| 406 | /* gdtc is !NULL iff @dtc is for memcg domain */ |
| 407 | if (gdtc) { |
| 408 | unsigned long global_avail = gdtc->avail; |
| 409 | |
| 410 | /* |
| 411 | * The byte settings can't be applied directly to memcg |
| 412 | * domains. Convert them to ratios by scaling against |
Tejun Heo | 62a584f | 2016-05-27 14:34:46 -0400 | [diff] [blame] | 413 | * globally available memory. As the ratios are in |
| 414 | * per-PAGE_SIZE, they can be obtained by dividing bytes by |
| 415 | * number of pages. |
Tejun Heo | 9fc3a43 | 2015-05-22 18:23:30 -0400 | [diff] [blame] | 416 | */ |
| 417 | if (bytes) |
Tejun Heo | 62a584f | 2016-05-27 14:34:46 -0400 | [diff] [blame] | 418 | ratio = min(DIV_ROUND_UP(bytes, global_avail), |
| 419 | PAGE_SIZE); |
Tejun Heo | 9fc3a43 | 2015-05-22 18:23:30 -0400 | [diff] [blame] | 420 | if (bg_bytes) |
Tejun Heo | 62a584f | 2016-05-27 14:34:46 -0400 | [diff] [blame] | 421 | bg_ratio = min(DIV_ROUND_UP(bg_bytes, global_avail), |
| 422 | PAGE_SIZE); |
Tejun Heo | 9fc3a43 | 2015-05-22 18:23:30 -0400 | [diff] [blame] | 423 | bytes = bg_bytes = 0; |
| 424 | } |
| 425 | |
| 426 | if (bytes) |
| 427 | thresh = DIV_ROUND_UP(bytes, PAGE_SIZE); |
| 428 | else |
Tejun Heo | 62a584f | 2016-05-27 14:34:46 -0400 | [diff] [blame] | 429 | thresh = (ratio * available_memory) / PAGE_SIZE; |
Tejun Heo | 9fc3a43 | 2015-05-22 18:23:30 -0400 | [diff] [blame] | 430 | |
| 431 | if (bg_bytes) |
| 432 | bg_thresh = DIV_ROUND_UP(bg_bytes, PAGE_SIZE); |
| 433 | else |
Tejun Heo | 62a584f | 2016-05-27 14:34:46 -0400 | [diff] [blame] | 434 | bg_thresh = (bg_ratio * available_memory) / PAGE_SIZE; |
Tejun Heo | 9fc3a43 | 2015-05-22 18:23:30 -0400 | [diff] [blame] | 435 | |
Michal Hocko | 90daf30 | 2017-11-29 16:10:58 -0800 | [diff] [blame] | 436 | if (bg_thresh >= thresh) |
Tejun Heo | 9fc3a43 | 2015-05-22 18:23:30 -0400 | [diff] [blame] | 437 | bg_thresh = thresh / 2; |
| 438 | tsk = current; |
| 439 | if (tsk->flags & PF_LESS_THROTTLE || rt_task(tsk)) { |
NeilBrown | a53eaff | 2016-05-20 16:58:53 -0700 | [diff] [blame] | 440 | bg_thresh += bg_thresh / 4 + global_wb_domain.dirty_limit / 32; |
| 441 | thresh += thresh / 4 + global_wb_domain.dirty_limit / 32; |
Tejun Heo | 9fc3a43 | 2015-05-22 18:23:30 -0400 | [diff] [blame] | 442 | } |
| 443 | dtc->thresh = thresh; |
| 444 | dtc->bg_thresh = bg_thresh; |
| 445 | |
| 446 | /* we should eventually report the domain in the TP */ |
| 447 | if (!gdtc) |
| 448 | trace_global_dirty_state(bg_thresh, thresh); |
| 449 | } |
| 450 | |
| 451 | /** |
| 452 | * global_dirty_limits - background-writeback and dirty-throttling thresholds |
| 453 | * @pbackground: out parameter for bg_thresh |
| 454 | * @pdirty: out parameter for thresh |
| 455 | * |
| 456 | * Calculate bg_thresh and thresh for global_wb_domain. See |
| 457 | * domain_dirty_limits() for details. |
| 458 | */ |
Johannes Weiner | ccafa28 | 2012-01-10 15:07:44 -0800 | [diff] [blame] | 459 | void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty) |
| 460 | { |
Tejun Heo | 9fc3a43 | 2015-05-22 18:23:30 -0400 | [diff] [blame] | 461 | struct dirty_throttle_control gdtc = { GDTC_INIT_NO_WB }; |
Johannes Weiner | ccafa28 | 2012-01-10 15:07:44 -0800 | [diff] [blame] | 462 | |
Tejun Heo | 9fc3a43 | 2015-05-22 18:23:30 -0400 | [diff] [blame] | 463 | gdtc.avail = global_dirtyable_memory(); |
| 464 | domain_dirty_limits(&gdtc); |
Johannes Weiner | ccafa28 | 2012-01-10 15:07:44 -0800 | [diff] [blame] | 465 | |
Tejun Heo | 9fc3a43 | 2015-05-22 18:23:30 -0400 | [diff] [blame] | 466 | *pbackground = gdtc.bg_thresh; |
| 467 | *pdirty = gdtc.thresh; |
Johannes Weiner | ccafa28 | 2012-01-10 15:07:44 -0800 | [diff] [blame] | 468 | } |
| 469 | |
Johannes Weiner | a756cf5 | 2012-01-10 15:07:49 -0800 | [diff] [blame] | 470 | /** |
Mel Gorman | 281e372 | 2016-07-28 15:46:11 -0700 | [diff] [blame] | 471 | * node_dirty_limit - maximum number of dirty pages allowed in a node |
| 472 | * @pgdat: the node |
Johannes Weiner | a756cf5 | 2012-01-10 15:07:49 -0800 | [diff] [blame] | 473 | * |
Mel Gorman | 281e372 | 2016-07-28 15:46:11 -0700 | [diff] [blame] | 474 | * Returns the maximum number of dirty pages allowed in a node, based |
| 475 | * on the node's dirtyable memory. |
Johannes Weiner | a756cf5 | 2012-01-10 15:07:49 -0800 | [diff] [blame] | 476 | */ |
Mel Gorman | 281e372 | 2016-07-28 15:46:11 -0700 | [diff] [blame] | 477 | static unsigned long node_dirty_limit(struct pglist_data *pgdat) |
Johannes Weiner | a756cf5 | 2012-01-10 15:07:49 -0800 | [diff] [blame] | 478 | { |
Mel Gorman | 281e372 | 2016-07-28 15:46:11 -0700 | [diff] [blame] | 479 | unsigned long node_memory = node_dirtyable_memory(pgdat); |
Johannes Weiner | a756cf5 | 2012-01-10 15:07:49 -0800 | [diff] [blame] | 480 | struct task_struct *tsk = current; |
| 481 | unsigned long dirty; |
| 482 | |
| 483 | if (vm_dirty_bytes) |
| 484 | dirty = DIV_ROUND_UP(vm_dirty_bytes, PAGE_SIZE) * |
Mel Gorman | 281e372 | 2016-07-28 15:46:11 -0700 | [diff] [blame] | 485 | node_memory / global_dirtyable_memory(); |
Johannes Weiner | a756cf5 | 2012-01-10 15:07:49 -0800 | [diff] [blame] | 486 | else |
Mel Gorman | 281e372 | 2016-07-28 15:46:11 -0700 | [diff] [blame] | 487 | dirty = vm_dirty_ratio * node_memory / 100; |
Johannes Weiner | a756cf5 | 2012-01-10 15:07:49 -0800 | [diff] [blame] | 488 | |
| 489 | if (tsk->flags & PF_LESS_THROTTLE || rt_task(tsk)) |
| 490 | dirty += dirty / 4; |
| 491 | |
| 492 | return dirty; |
| 493 | } |
| 494 | |
| 495 | /** |
Mel Gorman | 281e372 | 2016-07-28 15:46:11 -0700 | [diff] [blame] | 496 | * node_dirty_ok - tells whether a node is within its dirty limits |
| 497 | * @pgdat: the node to check |
Johannes Weiner | a756cf5 | 2012-01-10 15:07:49 -0800 | [diff] [blame] | 498 | * |
Mel Gorman | 281e372 | 2016-07-28 15:46:11 -0700 | [diff] [blame] | 499 | * Returns %true when the dirty pages in @pgdat are within the node's |
Johannes Weiner | a756cf5 | 2012-01-10 15:07:49 -0800 | [diff] [blame] | 500 | * dirty limit, %false if the limit is exceeded. |
| 501 | */ |
Mel Gorman | 281e372 | 2016-07-28 15:46:11 -0700 | [diff] [blame] | 502 | bool node_dirty_ok(struct pglist_data *pgdat) |
Johannes Weiner | a756cf5 | 2012-01-10 15:07:49 -0800 | [diff] [blame] | 503 | { |
Mel Gorman | 281e372 | 2016-07-28 15:46:11 -0700 | [diff] [blame] | 504 | unsigned long limit = node_dirty_limit(pgdat); |
| 505 | unsigned long nr_pages = 0; |
Johannes Weiner | a756cf5 | 2012-01-10 15:07:49 -0800 | [diff] [blame] | 506 | |
Mel Gorman | 11fb998 | 2016-07-28 15:46:20 -0700 | [diff] [blame] | 507 | nr_pages += node_page_state(pgdat, NR_FILE_DIRTY); |
| 508 | nr_pages += node_page_state(pgdat, NR_UNSTABLE_NFS); |
| 509 | nr_pages += node_page_state(pgdat, NR_WRITEBACK); |
Mel Gorman | 281e372 | 2016-07-28 15:46:11 -0700 | [diff] [blame] | 510 | |
| 511 | return nr_pages <= limit; |
Johannes Weiner | a756cf5 | 2012-01-10 15:07:49 -0800 | [diff] [blame] | 512 | } |
| 513 | |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 514 | int dirty_background_ratio_handler(struct ctl_table *table, int write, |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 515 | void __user *buffer, size_t *lenp, |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 516 | loff_t *ppos) |
| 517 | { |
| 518 | int ret; |
| 519 | |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 520 | ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 521 | if (ret == 0 && write) |
| 522 | dirty_background_bytes = 0; |
| 523 | return ret; |
| 524 | } |
| 525 | |
| 526 | int dirty_background_bytes_handler(struct ctl_table *table, int write, |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 527 | void __user *buffer, size_t *lenp, |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 528 | loff_t *ppos) |
| 529 | { |
| 530 | int ret; |
| 531 | |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 532 | ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos); |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 533 | if (ret == 0 && write) |
| 534 | dirty_background_ratio = 0; |
| 535 | return ret; |
| 536 | } |
| 537 | |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 538 | int dirty_ratio_handler(struct ctl_table *table, int write, |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 539 | void __user *buffer, size_t *lenp, |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 540 | loff_t *ppos) |
| 541 | { |
| 542 | int old_ratio = vm_dirty_ratio; |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 543 | int ret; |
| 544 | |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 545 | ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 546 | if (ret == 0 && write && vm_dirty_ratio != old_ratio) { |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 547 | writeback_set_ratelimit(); |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 548 | vm_dirty_bytes = 0; |
| 549 | } |
| 550 | return ret; |
| 551 | } |
| 552 | |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 553 | int dirty_bytes_handler(struct ctl_table *table, int write, |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 554 | void __user *buffer, size_t *lenp, |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 555 | loff_t *ppos) |
| 556 | { |
Sven Wegener | fc3501d | 2009-02-11 13:04:23 -0800 | [diff] [blame] | 557 | unsigned long old_bytes = vm_dirty_bytes; |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 558 | int ret; |
| 559 | |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 560 | ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos); |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 561 | if (ret == 0 && write && vm_dirty_bytes != old_bytes) { |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 562 | writeback_set_ratelimit(); |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 563 | vm_dirty_ratio = 0; |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 564 | } |
| 565 | return ret; |
| 566 | } |
| 567 | |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 568 | static unsigned long wp_next_time(unsigned long cur_time) |
| 569 | { |
| 570 | cur_time += VM_COMPLETIONS_PERIOD_LEN; |
| 571 | /* 0 has a special meaning... */ |
| 572 | if (!cur_time) |
| 573 | return 1; |
| 574 | return cur_time; |
| 575 | } |
| 576 | |
Tejun Heo | c798143 | 2015-05-22 18:23:29 -0400 | [diff] [blame] | 577 | static void wb_domain_writeout_inc(struct wb_domain *dom, |
| 578 | struct fprop_local_percpu *completions, |
| 579 | unsigned int max_prop_frac) |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 580 | { |
Tejun Heo | c798143 | 2015-05-22 18:23:29 -0400 | [diff] [blame] | 581 | __fprop_inc_percpu_max(&dom->completions, completions, |
| 582 | max_prop_frac); |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 583 | /* First event after period switching was turned off? */ |
Steven Rostedt (VMware) | 517663e | 2017-02-24 14:59:24 -0800 | [diff] [blame] | 584 | if (unlikely(!dom->period_time)) { |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 585 | /* |
| 586 | * We can race with other __bdi_writeout_inc calls here but |
| 587 | * it does not cause any harm since the resulting time when |
| 588 | * timer will fire and what is in writeout_period_time will be |
| 589 | * roughly the same. |
| 590 | */ |
Tejun Heo | 380c27c | 2015-05-22 18:23:21 -0400 | [diff] [blame] | 591 | dom->period_time = wp_next_time(jiffies); |
| 592 | mod_timer(&dom->period_timer, dom->period_time); |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 593 | } |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 594 | } |
| 595 | |
Tejun Heo | c798143 | 2015-05-22 18:23:29 -0400 | [diff] [blame] | 596 | /* |
| 597 | * Increment @wb's writeout completion count and the global writeout |
| 598 | * completion count. Called from test_clear_page_writeback(). |
| 599 | */ |
| 600 | static inline void __wb_writeout_inc(struct bdi_writeback *wb) |
| 601 | { |
Tejun Heo | 841710a | 2015-05-22 18:23:33 -0400 | [diff] [blame] | 602 | struct wb_domain *cgdom; |
| 603 | |
Nikolay Borisov | 3e8f399 | 2017-07-12 14:37:51 -0700 | [diff] [blame] | 604 | inc_wb_stat(wb, WB_WRITTEN); |
Tejun Heo | c798143 | 2015-05-22 18:23:29 -0400 | [diff] [blame] | 605 | wb_domain_writeout_inc(&global_wb_domain, &wb->completions, |
| 606 | wb->bdi->max_prop_frac); |
Tejun Heo | 841710a | 2015-05-22 18:23:33 -0400 | [diff] [blame] | 607 | |
| 608 | cgdom = mem_cgroup_wb_domain(wb); |
| 609 | if (cgdom) |
| 610 | wb_domain_writeout_inc(cgdom, wb_memcg_completions(wb), |
| 611 | wb->bdi->max_prop_frac); |
Tejun Heo | c798143 | 2015-05-22 18:23:29 -0400 | [diff] [blame] | 612 | } |
| 613 | |
Tejun Heo | 93f78d8 | 2015-05-22 17:13:27 -0400 | [diff] [blame] | 614 | void wb_writeout_inc(struct bdi_writeback *wb) |
Miklos Szeredi | dd5656e | 2008-04-30 00:54:37 -0700 | [diff] [blame] | 615 | { |
| 616 | unsigned long flags; |
| 617 | |
| 618 | local_irq_save(flags); |
Tejun Heo | 93f78d8 | 2015-05-22 17:13:27 -0400 | [diff] [blame] | 619 | __wb_writeout_inc(wb); |
Miklos Szeredi | dd5656e | 2008-04-30 00:54:37 -0700 | [diff] [blame] | 620 | local_irq_restore(flags); |
| 621 | } |
Tejun Heo | 93f78d8 | 2015-05-22 17:13:27 -0400 | [diff] [blame] | 622 | EXPORT_SYMBOL_GPL(wb_writeout_inc); |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 623 | |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 624 | /* |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 625 | * On idle system, we can be called long after we scheduled because we use |
| 626 | * deferred timers so count with missed periods. |
| 627 | */ |
Kees Cook | 9823e51 | 2017-11-15 17:37:04 -0800 | [diff] [blame] | 628 | static void writeout_period(struct timer_list *t) |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 629 | { |
Kees Cook | 9823e51 | 2017-11-15 17:37:04 -0800 | [diff] [blame] | 630 | struct wb_domain *dom = from_timer(dom, t, period_timer); |
Tejun Heo | 380c27c | 2015-05-22 18:23:21 -0400 | [diff] [blame] | 631 | int miss_periods = (jiffies - dom->period_time) / |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 632 | VM_COMPLETIONS_PERIOD_LEN; |
| 633 | |
Tejun Heo | 380c27c | 2015-05-22 18:23:21 -0400 | [diff] [blame] | 634 | if (fprop_new_period(&dom->completions, miss_periods + 1)) { |
| 635 | dom->period_time = wp_next_time(dom->period_time + |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 636 | miss_periods * VM_COMPLETIONS_PERIOD_LEN); |
Tejun Heo | 380c27c | 2015-05-22 18:23:21 -0400 | [diff] [blame] | 637 | mod_timer(&dom->period_timer, dom->period_time); |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 638 | } else { |
| 639 | /* |
| 640 | * Aging has zeroed all fractions. Stop wasting CPU on period |
| 641 | * updates. |
| 642 | */ |
Tejun Heo | 380c27c | 2015-05-22 18:23:21 -0400 | [diff] [blame] | 643 | dom->period_time = 0; |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 644 | } |
| 645 | } |
| 646 | |
Tejun Heo | 380c27c | 2015-05-22 18:23:21 -0400 | [diff] [blame] | 647 | int wb_domain_init(struct wb_domain *dom, gfp_t gfp) |
| 648 | { |
| 649 | memset(dom, 0, sizeof(*dom)); |
Tejun Heo | dcc25ae | 2015-05-22 18:23:22 -0400 | [diff] [blame] | 650 | |
| 651 | spin_lock_init(&dom->lock); |
| 652 | |
Kees Cook | 9823e51 | 2017-11-15 17:37:04 -0800 | [diff] [blame] | 653 | timer_setup(&dom->period_timer, writeout_period, TIMER_DEFERRABLE); |
Tejun Heo | dcc25ae | 2015-05-22 18:23:22 -0400 | [diff] [blame] | 654 | |
| 655 | dom->dirty_limit_tstamp = jiffies; |
| 656 | |
Tejun Heo | 380c27c | 2015-05-22 18:23:21 -0400 | [diff] [blame] | 657 | return fprop_global_init(&dom->completions, gfp); |
| 658 | } |
| 659 | |
Tejun Heo | 841710a | 2015-05-22 18:23:33 -0400 | [diff] [blame] | 660 | #ifdef CONFIG_CGROUP_WRITEBACK |
| 661 | void wb_domain_exit(struct wb_domain *dom) |
| 662 | { |
| 663 | del_timer_sync(&dom->period_timer); |
| 664 | fprop_global_destroy(&dom->completions); |
| 665 | } |
| 666 | #endif |
| 667 | |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 668 | /* |
Johannes Weiner | d08c429 | 2011-10-31 17:07:05 -0700 | [diff] [blame] | 669 | * bdi_min_ratio keeps the sum of the minimum dirty shares of all |
| 670 | * registered backing devices, which, for obvious reasons, can not |
| 671 | * exceed 100%. |
Peter Zijlstra | 189d3c4 | 2008-04-30 00:54:35 -0700 | [diff] [blame] | 672 | */ |
Peter Zijlstra | 189d3c4 | 2008-04-30 00:54:35 -0700 | [diff] [blame] | 673 | static unsigned int bdi_min_ratio; |
| 674 | |
| 675 | int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio) |
| 676 | { |
| 677 | int ret = 0; |
Peter Zijlstra | 189d3c4 | 2008-04-30 00:54:35 -0700 | [diff] [blame] | 678 | |
Jens Axboe | cfc4ba5 | 2009-09-14 13:12:40 +0200 | [diff] [blame] | 679 | spin_lock_bh(&bdi_lock); |
Peter Zijlstra | a42dde0 | 2008-04-30 00:54:36 -0700 | [diff] [blame] | 680 | if (min_ratio > bdi->max_ratio) { |
Peter Zijlstra | 189d3c4 | 2008-04-30 00:54:35 -0700 | [diff] [blame] | 681 | ret = -EINVAL; |
Peter Zijlstra | a42dde0 | 2008-04-30 00:54:36 -0700 | [diff] [blame] | 682 | } else { |
| 683 | min_ratio -= bdi->min_ratio; |
| 684 | if (bdi_min_ratio + min_ratio < 100) { |
| 685 | bdi_min_ratio += min_ratio; |
| 686 | bdi->min_ratio += min_ratio; |
| 687 | } else { |
| 688 | ret = -EINVAL; |
| 689 | } |
| 690 | } |
Jens Axboe | cfc4ba5 | 2009-09-14 13:12:40 +0200 | [diff] [blame] | 691 | spin_unlock_bh(&bdi_lock); |
Peter Zijlstra | 189d3c4 | 2008-04-30 00:54:35 -0700 | [diff] [blame] | 692 | |
| 693 | return ret; |
| 694 | } |
| 695 | |
Peter Zijlstra | a42dde0 | 2008-04-30 00:54:36 -0700 | [diff] [blame] | 696 | int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned max_ratio) |
| 697 | { |
Peter Zijlstra | a42dde0 | 2008-04-30 00:54:36 -0700 | [diff] [blame] | 698 | int ret = 0; |
| 699 | |
| 700 | if (max_ratio > 100) |
| 701 | return -EINVAL; |
| 702 | |
Jens Axboe | cfc4ba5 | 2009-09-14 13:12:40 +0200 | [diff] [blame] | 703 | spin_lock_bh(&bdi_lock); |
Peter Zijlstra | a42dde0 | 2008-04-30 00:54:36 -0700 | [diff] [blame] | 704 | if (bdi->min_ratio > max_ratio) { |
| 705 | ret = -EINVAL; |
| 706 | } else { |
| 707 | bdi->max_ratio = max_ratio; |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 708 | bdi->max_prop_frac = (FPROP_FRAC_BASE * max_ratio) / 100; |
Peter Zijlstra | a42dde0 | 2008-04-30 00:54:36 -0700 | [diff] [blame] | 709 | } |
Jens Axboe | cfc4ba5 | 2009-09-14 13:12:40 +0200 | [diff] [blame] | 710 | spin_unlock_bh(&bdi_lock); |
Peter Zijlstra | a42dde0 | 2008-04-30 00:54:36 -0700 | [diff] [blame] | 711 | |
| 712 | return ret; |
| 713 | } |
| 714 | EXPORT_SYMBOL(bdi_set_max_ratio); |
| 715 | |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 716 | static unsigned long dirty_freerun_ceiling(unsigned long thresh, |
| 717 | unsigned long bg_thresh) |
| 718 | { |
| 719 | return (thresh + bg_thresh) / 2; |
| 720 | } |
| 721 | |
Tejun Heo | c798143 | 2015-05-22 18:23:29 -0400 | [diff] [blame] | 722 | static unsigned long hard_dirty_limit(struct wb_domain *dom, |
| 723 | unsigned long thresh) |
Wu Fengguang | ffd1f60 | 2011-06-19 22:18:42 -0600 | [diff] [blame] | 724 | { |
Tejun Heo | dcc25ae | 2015-05-22 18:23:22 -0400 | [diff] [blame] | 725 | return max(thresh, dom->dirty_limit); |
Wu Fengguang | ffd1f60 | 2011-06-19 22:18:42 -0600 | [diff] [blame] | 726 | } |
| 727 | |
Tejun Heo | c5edf9c | 2015-09-29 13:04:26 -0400 | [diff] [blame] | 728 | /* |
| 729 | * Memory which can be further allocated to a memcg domain is capped by |
| 730 | * system-wide clean memory excluding the amount being used in the domain. |
| 731 | */ |
| 732 | static void mdtc_calc_avail(struct dirty_throttle_control *mdtc, |
| 733 | unsigned long filepages, unsigned long headroom) |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 734 | { |
| 735 | struct dirty_throttle_control *gdtc = mdtc_gdtc(mdtc); |
Tejun Heo | c5edf9c | 2015-09-29 13:04:26 -0400 | [diff] [blame] | 736 | unsigned long clean = filepages - min(filepages, mdtc->dirty); |
| 737 | unsigned long global_clean = gdtc->avail - min(gdtc->avail, gdtc->dirty); |
| 738 | unsigned long other_clean = global_clean - min(global_clean, clean); |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 739 | |
Tejun Heo | c5edf9c | 2015-09-29 13:04:26 -0400 | [diff] [blame] | 740 | mdtc->avail = filepages + min(headroom, other_clean); |
Christoph Lameter | 1b42446 | 2007-05-06 14:48:59 -0700 | [diff] [blame] | 741 | } |
| 742 | |
Wu Fengguang | 6f71865 | 2011-03-02 17:14:34 -0600 | [diff] [blame] | 743 | /** |
Tejun Heo | b1cbc6d | 2015-05-22 18:23:25 -0400 | [diff] [blame] | 744 | * __wb_calc_thresh - @wb's share of dirty throttling threshold |
| 745 | * @dtc: dirty_throttle_context of interest |
Wu Fengguang | 1babe18 | 2010-08-11 14:17:40 -0700 | [diff] [blame] | 746 | * |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 747 | * Returns @wb's dirty limit in pages. The term "dirty" in the context of |
Wu Fengguang | 6f71865 | 2011-03-02 17:14:34 -0600 | [diff] [blame] | 748 | * dirty balancing includes all PG_dirty, PG_writeback and NFS unstable pages. |
Wu Fengguang | aed21ad | 2011-11-23 11:44:41 -0600 | [diff] [blame] | 749 | * |
| 750 | * Note that balance_dirty_pages() will only seriously take it as a hard limit |
| 751 | * when sleeping max_pause per page is not enough to keep the dirty pages under |
| 752 | * control. For example, when the device is completely stalled due to some error |
| 753 | * conditions, or when there are 1000 dd tasks writing to a slow 10MB/s USB key. |
| 754 | * In the other normal situations, it acts more gently by throttling the tasks |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 755 | * more (rather than completely block them) when the wb dirty pages go high. |
Wu Fengguang | 6f71865 | 2011-03-02 17:14:34 -0600 | [diff] [blame] | 756 | * |
| 757 | * It allocates high/low dirty limits to fast/slow devices, in order to prevent |
Wu Fengguang | 1babe18 | 2010-08-11 14:17:40 -0700 | [diff] [blame] | 758 | * - starving fast devices |
| 759 | * - piling up dirty pages (that will take long time to sync) on slow devices |
| 760 | * |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 761 | * The wb's share of dirty limit will be adapting to its throughput and |
Wu Fengguang | 1babe18 | 2010-08-11 14:17:40 -0700 | [diff] [blame] | 762 | * bounded by the bdi->min_ratio and/or bdi->max_ratio parameters, if set. |
| 763 | */ |
Tejun Heo | b1cbc6d | 2015-05-22 18:23:25 -0400 | [diff] [blame] | 764 | static unsigned long __wb_calc_thresh(struct dirty_throttle_control *dtc) |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 765 | { |
Tejun Heo | e9f07df | 2015-05-22 18:23:28 -0400 | [diff] [blame] | 766 | struct wb_domain *dom = dtc_dom(dtc); |
Tejun Heo | b1cbc6d | 2015-05-22 18:23:25 -0400 | [diff] [blame] | 767 | unsigned long thresh = dtc->thresh; |
Tejun Heo | 0d960a3 | 2015-05-22 18:23:19 -0400 | [diff] [blame] | 768 | u64 wb_thresh; |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 769 | long numerator, denominator; |
Tejun Heo | 693108a | 2015-05-22 17:13:49 -0400 | [diff] [blame] | 770 | unsigned long wb_min_ratio, wb_max_ratio; |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 771 | |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 772 | /* |
Tejun Heo | 0d960a3 | 2015-05-22 18:23:19 -0400 | [diff] [blame] | 773 | * Calculate this BDI's share of the thresh ratio. |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 774 | */ |
Tejun Heo | e9770b3 | 2015-05-22 18:23:27 -0400 | [diff] [blame] | 775 | fprop_fraction_percpu(&dom->completions, dtc->wb_completions, |
Tejun Heo | 380c27c | 2015-05-22 18:23:21 -0400 | [diff] [blame] | 776 | &numerator, &denominator); |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 777 | |
Tejun Heo | 0d960a3 | 2015-05-22 18:23:19 -0400 | [diff] [blame] | 778 | wb_thresh = (thresh * (100 - bdi_min_ratio)) / 100; |
| 779 | wb_thresh *= numerator; |
| 780 | do_div(wb_thresh, denominator); |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 781 | |
Tejun Heo | b1cbc6d | 2015-05-22 18:23:25 -0400 | [diff] [blame] | 782 | wb_min_max_ratio(dtc->wb, &wb_min_ratio, &wb_max_ratio); |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 783 | |
Tejun Heo | 0d960a3 | 2015-05-22 18:23:19 -0400 | [diff] [blame] | 784 | wb_thresh += (thresh * wb_min_ratio) / 100; |
| 785 | if (wb_thresh > (thresh * wb_max_ratio) / 100) |
| 786 | wb_thresh = thresh * wb_max_ratio / 100; |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 787 | |
Tejun Heo | 0d960a3 | 2015-05-22 18:23:19 -0400 | [diff] [blame] | 788 | return wb_thresh; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 789 | } |
| 790 | |
Tejun Heo | b1cbc6d | 2015-05-22 18:23:25 -0400 | [diff] [blame] | 791 | unsigned long wb_calc_thresh(struct bdi_writeback *wb, unsigned long thresh) |
| 792 | { |
| 793 | struct dirty_throttle_control gdtc = { GDTC_INIT(wb), |
| 794 | .thresh = thresh }; |
| 795 | return __wb_calc_thresh(&gdtc); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 796 | } |
| 797 | |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 798 | /* |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 799 | * setpoint - dirty 3 |
| 800 | * f(dirty) := 1.0 + (----------------) |
| 801 | * limit - setpoint |
| 802 | * |
| 803 | * it's a 3rd order polynomial that subjects to |
| 804 | * |
| 805 | * (1) f(freerun) = 2.0 => rampup dirty_ratelimit reasonably fast |
| 806 | * (2) f(setpoint) = 1.0 => the balance point |
| 807 | * (3) f(limit) = 0 => the hard limit |
| 808 | * (4) df/dx <= 0 => negative feedback control |
| 809 | * (5) the closer to setpoint, the smaller |df/dx| (and the reverse) |
| 810 | * => fast response on large errors; small oscillation near setpoint |
| 811 | */ |
Rik van Riel | d5c9fde | 2014-05-06 12:50:01 -0700 | [diff] [blame] | 812 | static long long pos_ratio_polynom(unsigned long setpoint, |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 813 | unsigned long dirty, |
| 814 | unsigned long limit) |
| 815 | { |
| 816 | long long pos_ratio; |
| 817 | long x; |
| 818 | |
Rik van Riel | d5c9fde | 2014-05-06 12:50:01 -0700 | [diff] [blame] | 819 | x = div64_s64(((s64)setpoint - (s64)dirty) << RATELIMIT_CALC_SHIFT, |
Tejun Heo | 464d138 | 2015-04-21 16:49:13 -0400 | [diff] [blame] | 820 | (limit - setpoint) | 1); |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 821 | pos_ratio = x; |
| 822 | pos_ratio = pos_ratio * x >> RATELIMIT_CALC_SHIFT; |
| 823 | pos_ratio = pos_ratio * x >> RATELIMIT_CALC_SHIFT; |
| 824 | pos_ratio += 1 << RATELIMIT_CALC_SHIFT; |
| 825 | |
| 826 | return clamp(pos_ratio, 0LL, 2LL << RATELIMIT_CALC_SHIFT); |
| 827 | } |
| 828 | |
| 829 | /* |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 830 | * Dirty position control. |
| 831 | * |
| 832 | * (o) global/bdi setpoints |
| 833 | * |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 834 | * We want the dirty pages be balanced around the global/wb setpoints. |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 835 | * When the number of dirty pages is higher/lower than the setpoint, the |
| 836 | * dirty position control ratio (and hence task dirty ratelimit) will be |
| 837 | * decreased/increased to bring the dirty pages back to the setpoint. |
| 838 | * |
| 839 | * pos_ratio = 1 << RATELIMIT_CALC_SHIFT |
| 840 | * |
| 841 | * if (dirty < setpoint) scale up pos_ratio |
| 842 | * if (dirty > setpoint) scale down pos_ratio |
| 843 | * |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 844 | * if (wb_dirty < wb_setpoint) scale up pos_ratio |
| 845 | * if (wb_dirty > wb_setpoint) scale down pos_ratio |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 846 | * |
| 847 | * task_ratelimit = dirty_ratelimit * pos_ratio >> RATELIMIT_CALC_SHIFT |
| 848 | * |
| 849 | * (o) global control line |
| 850 | * |
| 851 | * ^ pos_ratio |
| 852 | * | |
| 853 | * | |<===== global dirty control scope ======>| |
| 854 | * 2.0 .............* |
| 855 | * | .* |
| 856 | * | . * |
| 857 | * | . * |
| 858 | * | . * |
| 859 | * | . * |
| 860 | * | . * |
| 861 | * 1.0 ................................* |
| 862 | * | . . * |
| 863 | * | . . * |
| 864 | * | . . * |
| 865 | * | . . * |
| 866 | * | . . * |
| 867 | * 0 +------------.------------------.----------------------*-------------> |
| 868 | * freerun^ setpoint^ limit^ dirty pages |
| 869 | * |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 870 | * (o) wb control line |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 871 | * |
| 872 | * ^ pos_ratio |
| 873 | * | |
| 874 | * | * |
| 875 | * | * |
| 876 | * | * |
| 877 | * | * |
| 878 | * | * |<=========== span ============>| |
| 879 | * 1.0 .......................* |
| 880 | * | . * |
| 881 | * | . * |
| 882 | * | . * |
| 883 | * | . * |
| 884 | * | . * |
| 885 | * | . * |
| 886 | * | . * |
| 887 | * | . * |
| 888 | * | . * |
| 889 | * | . * |
| 890 | * | . * |
| 891 | * 1/4 ...............................................* * * * * * * * * * * * |
| 892 | * | . . |
| 893 | * | . . |
| 894 | * | . . |
| 895 | * 0 +----------------------.-------------------------------.-------------> |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 896 | * wb_setpoint^ x_intercept^ |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 897 | * |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 898 | * The wb control line won't drop below pos_ratio=1/4, so that wb_dirty can |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 899 | * be smoothly throttled down to normal if it starts high in situations like |
| 900 | * - start writing to a slow SD card and a fast disk at the same time. The SD |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 901 | * card's wb_dirty may rush to many times higher than wb_setpoint. |
| 902 | * - the wb dirty thresh drops quickly due to change of JBOD workload |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 903 | */ |
Tejun Heo | daddfa3 | 2015-05-22 18:23:26 -0400 | [diff] [blame] | 904 | static void wb_position_ratio(struct dirty_throttle_control *dtc) |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 905 | { |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 906 | struct bdi_writeback *wb = dtc->wb; |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 907 | unsigned long write_bw = wb->avg_write_bandwidth; |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 908 | unsigned long freerun = dirty_freerun_ceiling(dtc->thresh, dtc->bg_thresh); |
Tejun Heo | c798143 | 2015-05-22 18:23:29 -0400 | [diff] [blame] | 909 | unsigned long limit = hard_dirty_limit(dtc_dom(dtc), dtc->thresh); |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 910 | unsigned long wb_thresh = dtc->wb_thresh; |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 911 | unsigned long x_intercept; |
| 912 | unsigned long setpoint; /* dirty pages' target balance point */ |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 913 | unsigned long wb_setpoint; |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 914 | unsigned long span; |
| 915 | long long pos_ratio; /* for scaling up/down the rate limit */ |
| 916 | long x; |
| 917 | |
Tejun Heo | daddfa3 | 2015-05-22 18:23:26 -0400 | [diff] [blame] | 918 | dtc->pos_ratio = 0; |
| 919 | |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 920 | if (unlikely(dtc->dirty >= limit)) |
Tejun Heo | daddfa3 | 2015-05-22 18:23:26 -0400 | [diff] [blame] | 921 | return; |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 922 | |
| 923 | /* |
| 924 | * global setpoint |
| 925 | * |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 926 | * See comment for pos_ratio_polynom(). |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 927 | */ |
| 928 | setpoint = (freerun + limit) / 2; |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 929 | pos_ratio = pos_ratio_polynom(setpoint, dtc->dirty, limit); |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 930 | |
| 931 | /* |
| 932 | * The strictlimit feature is a tool preventing mistrusted filesystems |
| 933 | * from growing a large number of dirty pages before throttling. For |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 934 | * such filesystems balance_dirty_pages always checks wb counters |
| 935 | * against wb limits. Even if global "nr_dirty" is under "freerun". |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 936 | * This is especially important for fuse which sets bdi->max_ratio to |
| 937 | * 1% by default. Without strictlimit feature, fuse writeback may |
| 938 | * consume arbitrary amount of RAM because it is accounted in |
| 939 | * NR_WRITEBACK_TEMP which is not involved in calculating "nr_dirty". |
| 940 | * |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 941 | * Here, in wb_position_ratio(), we calculate pos_ratio based on |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 942 | * two values: wb_dirty and wb_thresh. Let's consider an example: |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 943 | * total amount of RAM is 16GB, bdi->max_ratio is equal to 1%, global |
| 944 | * limits are set by default to 10% and 20% (background and throttle). |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 945 | * Then wb_thresh is 1% of 20% of 16GB. This amounts to ~8K pages. |
Tejun Heo | 0d960a3 | 2015-05-22 18:23:19 -0400 | [diff] [blame] | 946 | * wb_calc_thresh(wb, bg_thresh) is about ~4K pages. wb_setpoint is |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 947 | * about ~6K pages (as the average of background and throttle wb |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 948 | * limits). The 3rd order polynomial will provide positive feedback if |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 949 | * wb_dirty is under wb_setpoint and vice versa. |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 950 | * |
| 951 | * Note, that we cannot use global counters in these calculations |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 952 | * because we want to throttle process writing to a strictlimit wb |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 953 | * much earlier than global "freerun" is reached (~23MB vs. ~2.3GB |
| 954 | * in the example above). |
| 955 | */ |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 956 | if (unlikely(wb->bdi->capabilities & BDI_CAP_STRICTLIMIT)) { |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 957 | long long wb_pos_ratio; |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 958 | |
Tejun Heo | daddfa3 | 2015-05-22 18:23:26 -0400 | [diff] [blame] | 959 | if (dtc->wb_dirty < 8) { |
| 960 | dtc->pos_ratio = min_t(long long, pos_ratio * 2, |
| 961 | 2 << RATELIMIT_CALC_SHIFT); |
| 962 | return; |
| 963 | } |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 964 | |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 965 | if (dtc->wb_dirty >= wb_thresh) |
Tejun Heo | daddfa3 | 2015-05-22 18:23:26 -0400 | [diff] [blame] | 966 | return; |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 967 | |
Tejun Heo | 970fb01 | 2015-05-22 18:23:24 -0400 | [diff] [blame] | 968 | wb_setpoint = dirty_freerun_ceiling(wb_thresh, |
| 969 | dtc->wb_bg_thresh); |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 970 | |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 971 | if (wb_setpoint == 0 || wb_setpoint == wb_thresh) |
Tejun Heo | daddfa3 | 2015-05-22 18:23:26 -0400 | [diff] [blame] | 972 | return; |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 973 | |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 974 | wb_pos_ratio = pos_ratio_polynom(wb_setpoint, dtc->wb_dirty, |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 975 | wb_thresh); |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 976 | |
| 977 | /* |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 978 | * Typically, for strictlimit case, wb_setpoint << setpoint |
| 979 | * and pos_ratio >> wb_pos_ratio. In the other words global |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 980 | * state ("dirty") is not limiting factor and we have to |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 981 | * make decision based on wb counters. But there is an |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 982 | * important case when global pos_ratio should get precedence: |
| 983 | * global limits are exceeded (e.g. due to activities on other |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 984 | * wb's) while given strictlimit wb is below limit. |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 985 | * |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 986 | * "pos_ratio * wb_pos_ratio" would work for the case above, |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 987 | * but it would look too non-natural for the case of all |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 988 | * activity in the system coming from a single strictlimit wb |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 989 | * with bdi->max_ratio == 100%. |
| 990 | * |
| 991 | * Note that min() below somewhat changes the dynamics of the |
| 992 | * control system. Normally, pos_ratio value can be well over 3 |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 993 | * (when globally we are at freerun and wb is well below wb |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 994 | * setpoint). Now the maximum pos_ratio in the same situation |
| 995 | * is 2. We might want to tweak this if we observe the control |
| 996 | * system is too slow to adapt. |
| 997 | */ |
Tejun Heo | daddfa3 | 2015-05-22 18:23:26 -0400 | [diff] [blame] | 998 | dtc->pos_ratio = min(pos_ratio, wb_pos_ratio); |
| 999 | return; |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1000 | } |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 1001 | |
| 1002 | /* |
| 1003 | * We have computed basic pos_ratio above based on global situation. If |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1004 | * the wb is over/under its share of dirty pages, we want to scale |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 1005 | * pos_ratio further down/up. That is done by the following mechanism. |
| 1006 | */ |
| 1007 | |
| 1008 | /* |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1009 | * wb setpoint |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 1010 | * |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1011 | * f(wb_dirty) := 1.0 + k * (wb_dirty - wb_setpoint) |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 1012 | * |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1013 | * x_intercept - wb_dirty |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 1014 | * := -------------------------- |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1015 | * x_intercept - wb_setpoint |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 1016 | * |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1017 | * The main wb control line is a linear function that subjects to |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 1018 | * |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1019 | * (1) f(wb_setpoint) = 1.0 |
| 1020 | * (2) k = - 1 / (8 * write_bw) (in single wb case) |
| 1021 | * or equally: x_intercept = wb_setpoint + 8 * write_bw |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 1022 | * |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1023 | * For single wb case, the dirty pages are observed to fluctuate |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 1024 | * regularly within range |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1025 | * [wb_setpoint - write_bw/2, wb_setpoint + write_bw/2] |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 1026 | * for various filesystems, where (2) can yield in a reasonable 12.5% |
| 1027 | * fluctuation range for pos_ratio. |
| 1028 | * |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1029 | * For JBOD case, wb_thresh (not wb_dirty!) could fluctuate up to its |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 1030 | * own size, so move the slope over accordingly and choose a slope that |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1031 | * yields 100% pos_ratio fluctuation on suddenly doubled wb_thresh. |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 1032 | */ |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1033 | if (unlikely(wb_thresh > dtc->thresh)) |
| 1034 | wb_thresh = dtc->thresh; |
Wu Fengguang | aed21ad | 2011-11-23 11:44:41 -0600 | [diff] [blame] | 1035 | /* |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1036 | * It's very possible that wb_thresh is close to 0 not because the |
Wu Fengguang | aed21ad | 2011-11-23 11:44:41 -0600 | [diff] [blame] | 1037 | * device is slow, but that it has remained inactive for long time. |
| 1038 | * Honour such devices a reasonable good (hopefully IO efficient) |
| 1039 | * threshold, so that the occasional writes won't be blocked and active |
| 1040 | * writes can rampup the threshold quickly. |
| 1041 | */ |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1042 | wb_thresh = max(wb_thresh, (limit - dtc->dirty) / 8); |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 1043 | /* |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1044 | * scale global setpoint to wb's: |
| 1045 | * wb_setpoint = setpoint * wb_thresh / thresh |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 1046 | */ |
Linus Torvalds | e4bc13a | 2015-06-25 16:00:17 -0700 | [diff] [blame] | 1047 | x = div_u64((u64)wb_thresh << 16, dtc->thresh | 1); |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1048 | wb_setpoint = setpoint * (u64)x >> 16; |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 1049 | /* |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1050 | * Use span=(8*write_bw) in single wb case as indicated by |
| 1051 | * (thresh - wb_thresh ~= 0) and transit to wb_thresh in JBOD case. |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 1052 | * |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1053 | * wb_thresh thresh - wb_thresh |
| 1054 | * span = --------- * (8 * write_bw) + ------------------ * wb_thresh |
| 1055 | * thresh thresh |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 1056 | */ |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1057 | span = (dtc->thresh - wb_thresh + 8 * write_bw) * (u64)x >> 16; |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1058 | x_intercept = wb_setpoint + span; |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 1059 | |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1060 | if (dtc->wb_dirty < x_intercept - span / 4) { |
| 1061 | pos_ratio = div64_u64(pos_ratio * (x_intercept - dtc->wb_dirty), |
Linus Torvalds | e4bc13a | 2015-06-25 16:00:17 -0700 | [diff] [blame] | 1062 | (x_intercept - wb_setpoint) | 1); |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 1063 | } else |
| 1064 | pos_ratio /= 4; |
| 1065 | |
Wu Fengguang | 8927f66 | 2011-08-04 22:16:46 -0600 | [diff] [blame] | 1066 | /* |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1067 | * wb reserve area, safeguard against dirty pool underrun and disk idle |
Wu Fengguang | 8927f66 | 2011-08-04 22:16:46 -0600 | [diff] [blame] | 1068 | * It may push the desired control point of global dirty pages higher |
| 1069 | * than setpoint. |
| 1070 | */ |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1071 | x_intercept = wb_thresh / 2; |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1072 | if (dtc->wb_dirty < x_intercept) { |
| 1073 | if (dtc->wb_dirty > x_intercept / 8) |
| 1074 | pos_ratio = div_u64(pos_ratio * x_intercept, |
| 1075 | dtc->wb_dirty); |
Wu Fengguang | 50657fc | 2011-10-11 17:06:33 -0600 | [diff] [blame] | 1076 | else |
Wu Fengguang | 8927f66 | 2011-08-04 22:16:46 -0600 | [diff] [blame] | 1077 | pos_ratio *= 8; |
| 1078 | } |
| 1079 | |
Tejun Heo | daddfa3 | 2015-05-22 18:23:26 -0400 | [diff] [blame] | 1080 | dtc->pos_ratio = pos_ratio; |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 1081 | } |
| 1082 | |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1083 | static void wb_update_write_bandwidth(struct bdi_writeback *wb, |
| 1084 | unsigned long elapsed, |
| 1085 | unsigned long written) |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1086 | { |
| 1087 | const unsigned long period = roundup_pow_of_two(3 * HZ); |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1088 | unsigned long avg = wb->avg_write_bandwidth; |
| 1089 | unsigned long old = wb->write_bandwidth; |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1090 | u64 bw; |
| 1091 | |
| 1092 | /* |
| 1093 | * bw = written * HZ / elapsed |
| 1094 | * |
| 1095 | * bw * elapsed + write_bandwidth * (period - elapsed) |
| 1096 | * write_bandwidth = --------------------------------------------------- |
| 1097 | * period |
Tejun Heo | c72efb6 | 2015-03-23 00:18:48 -0400 | [diff] [blame] | 1098 | * |
| 1099 | * @written may have decreased due to account_page_redirty(). |
| 1100 | * Avoid underflowing @bw calculation. |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1101 | */ |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1102 | bw = written - min(written, wb->written_stamp); |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1103 | bw *= HZ; |
| 1104 | if (unlikely(elapsed > period)) { |
| 1105 | do_div(bw, elapsed); |
| 1106 | avg = bw; |
| 1107 | goto out; |
| 1108 | } |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1109 | bw += (u64)wb->write_bandwidth * (period - elapsed); |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1110 | bw >>= ilog2(period); |
| 1111 | |
| 1112 | /* |
| 1113 | * one more level of smoothing, for filtering out sudden spikes |
| 1114 | */ |
| 1115 | if (avg > old && old >= (unsigned long)bw) |
| 1116 | avg -= (avg - old) >> 3; |
| 1117 | |
| 1118 | if (avg < old && old <= (unsigned long)bw) |
| 1119 | avg += (old - avg) >> 3; |
| 1120 | |
| 1121 | out: |
Tejun Heo | 95a46c6 | 2015-05-22 17:13:47 -0400 | [diff] [blame] | 1122 | /* keep avg > 0 to guarantee that tot > 0 if there are dirty wbs */ |
| 1123 | avg = max(avg, 1LU); |
| 1124 | if (wb_has_dirty_io(wb)) { |
| 1125 | long delta = avg - wb->avg_write_bandwidth; |
| 1126 | WARN_ON_ONCE(atomic_long_add_return(delta, |
| 1127 | &wb->bdi->tot_write_bandwidth) <= 0); |
| 1128 | } |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1129 | wb->write_bandwidth = bw; |
| 1130 | wb->avg_write_bandwidth = avg; |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1131 | } |
| 1132 | |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1133 | static void update_dirty_limit(struct dirty_throttle_control *dtc) |
Wu Fengguang | c42843f | 2011-03-02 15:54:09 -0600 | [diff] [blame] | 1134 | { |
Tejun Heo | e9f07df | 2015-05-22 18:23:28 -0400 | [diff] [blame] | 1135 | struct wb_domain *dom = dtc_dom(dtc); |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1136 | unsigned long thresh = dtc->thresh; |
Tejun Heo | dcc25ae | 2015-05-22 18:23:22 -0400 | [diff] [blame] | 1137 | unsigned long limit = dom->dirty_limit; |
Wu Fengguang | c42843f | 2011-03-02 15:54:09 -0600 | [diff] [blame] | 1138 | |
| 1139 | /* |
| 1140 | * Follow up in one step. |
| 1141 | */ |
| 1142 | if (limit < thresh) { |
| 1143 | limit = thresh; |
| 1144 | goto update; |
| 1145 | } |
| 1146 | |
| 1147 | /* |
| 1148 | * Follow down slowly. Use the higher one as the target, because thresh |
| 1149 | * may drop below dirty. This is exactly the reason to introduce |
Tejun Heo | dcc25ae | 2015-05-22 18:23:22 -0400 | [diff] [blame] | 1150 | * dom->dirty_limit which is guaranteed to lie above the dirty pages. |
Wu Fengguang | c42843f | 2011-03-02 15:54:09 -0600 | [diff] [blame] | 1151 | */ |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1152 | thresh = max(thresh, dtc->dirty); |
Wu Fengguang | c42843f | 2011-03-02 15:54:09 -0600 | [diff] [blame] | 1153 | if (limit > thresh) { |
| 1154 | limit -= (limit - thresh) >> 5; |
| 1155 | goto update; |
| 1156 | } |
| 1157 | return; |
| 1158 | update: |
Tejun Heo | dcc25ae | 2015-05-22 18:23:22 -0400 | [diff] [blame] | 1159 | dom->dirty_limit = limit; |
Wu Fengguang | c42843f | 2011-03-02 15:54:09 -0600 | [diff] [blame] | 1160 | } |
| 1161 | |
Tejun Heo | e9f07df | 2015-05-22 18:23:28 -0400 | [diff] [blame] | 1162 | static void domain_update_bandwidth(struct dirty_throttle_control *dtc, |
Wu Fengguang | c42843f | 2011-03-02 15:54:09 -0600 | [diff] [blame] | 1163 | unsigned long now) |
| 1164 | { |
Tejun Heo | e9f07df | 2015-05-22 18:23:28 -0400 | [diff] [blame] | 1165 | struct wb_domain *dom = dtc_dom(dtc); |
Wu Fengguang | c42843f | 2011-03-02 15:54:09 -0600 | [diff] [blame] | 1166 | |
| 1167 | /* |
| 1168 | * check locklessly first to optimize away locking for the most time |
| 1169 | */ |
Tejun Heo | dcc25ae | 2015-05-22 18:23:22 -0400 | [diff] [blame] | 1170 | if (time_before(now, dom->dirty_limit_tstamp + BANDWIDTH_INTERVAL)) |
Wu Fengguang | c42843f | 2011-03-02 15:54:09 -0600 | [diff] [blame] | 1171 | return; |
| 1172 | |
Tejun Heo | dcc25ae | 2015-05-22 18:23:22 -0400 | [diff] [blame] | 1173 | spin_lock(&dom->lock); |
| 1174 | if (time_after_eq(now, dom->dirty_limit_tstamp + BANDWIDTH_INTERVAL)) { |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1175 | update_dirty_limit(dtc); |
Tejun Heo | dcc25ae | 2015-05-22 18:23:22 -0400 | [diff] [blame] | 1176 | dom->dirty_limit_tstamp = now; |
Wu Fengguang | c42843f | 2011-03-02 15:54:09 -0600 | [diff] [blame] | 1177 | } |
Tejun Heo | dcc25ae | 2015-05-22 18:23:22 -0400 | [diff] [blame] | 1178 | spin_unlock(&dom->lock); |
Wu Fengguang | c42843f | 2011-03-02 15:54:09 -0600 | [diff] [blame] | 1179 | } |
| 1180 | |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 1181 | /* |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1182 | * Maintain wb->dirty_ratelimit, the base dirty throttle rate. |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 1183 | * |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1184 | * Normal wb tasks will be curbed at or below it in long term. |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 1185 | * Obviously it should be around (write_bw / N) when there are N dd tasks. |
| 1186 | */ |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1187 | static void wb_update_dirty_ratelimit(struct dirty_throttle_control *dtc, |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1188 | unsigned long dirtied, |
| 1189 | unsigned long elapsed) |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 1190 | { |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1191 | struct bdi_writeback *wb = dtc->wb; |
| 1192 | unsigned long dirty = dtc->dirty; |
| 1193 | unsigned long freerun = dirty_freerun_ceiling(dtc->thresh, dtc->bg_thresh); |
Tejun Heo | c798143 | 2015-05-22 18:23:29 -0400 | [diff] [blame] | 1194 | unsigned long limit = hard_dirty_limit(dtc_dom(dtc), dtc->thresh); |
Wu Fengguang | 7381131 | 2011-08-26 15:53:24 -0600 | [diff] [blame] | 1195 | unsigned long setpoint = (freerun + limit) / 2; |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1196 | unsigned long write_bw = wb->avg_write_bandwidth; |
| 1197 | unsigned long dirty_ratelimit = wb->dirty_ratelimit; |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 1198 | unsigned long dirty_rate; |
| 1199 | unsigned long task_ratelimit; |
| 1200 | unsigned long balanced_dirty_ratelimit; |
Wu Fengguang | 7381131 | 2011-08-26 15:53:24 -0600 | [diff] [blame] | 1201 | unsigned long step; |
| 1202 | unsigned long x; |
Andrey Ryabinin | d59b108 | 2016-03-15 14:55:27 -0700 | [diff] [blame] | 1203 | unsigned long shift; |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 1204 | |
| 1205 | /* |
| 1206 | * The dirty rate will match the writeout rate in long term, except |
| 1207 | * when dirty pages are truncated by userspace or re-dirtied by FS. |
| 1208 | */ |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1209 | dirty_rate = (dirtied - wb->dirtied_stamp) * HZ / elapsed; |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 1210 | |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 1211 | /* |
| 1212 | * task_ratelimit reflects each dd's dirty rate for the past 200ms. |
| 1213 | */ |
| 1214 | task_ratelimit = (u64)dirty_ratelimit * |
Tejun Heo | daddfa3 | 2015-05-22 18:23:26 -0400 | [diff] [blame] | 1215 | dtc->pos_ratio >> RATELIMIT_CALC_SHIFT; |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 1216 | task_ratelimit++; /* it helps rampup dirty_ratelimit from tiny values */ |
| 1217 | |
| 1218 | /* |
| 1219 | * A linear estimation of the "balanced" throttle rate. The theory is, |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1220 | * if there are N dd tasks, each throttled at task_ratelimit, the wb's |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 1221 | * dirty_rate will be measured to be (N * task_ratelimit). So the below |
| 1222 | * formula will yield the balanced rate limit (write_bw / N). |
| 1223 | * |
| 1224 | * Note that the expanded form is not a pure rate feedback: |
| 1225 | * rate_(i+1) = rate_(i) * (write_bw / dirty_rate) (1) |
| 1226 | * but also takes pos_ratio into account: |
| 1227 | * rate_(i+1) = rate_(i) * (write_bw / dirty_rate) * pos_ratio (2) |
| 1228 | * |
| 1229 | * (1) is not realistic because pos_ratio also takes part in balancing |
| 1230 | * the dirty rate. Consider the state |
| 1231 | * pos_ratio = 0.5 (3) |
| 1232 | * rate = 2 * (write_bw / N) (4) |
| 1233 | * If (1) is used, it will stuck in that state! Because each dd will |
| 1234 | * be throttled at |
| 1235 | * task_ratelimit = pos_ratio * rate = (write_bw / N) (5) |
| 1236 | * yielding |
| 1237 | * dirty_rate = N * task_ratelimit = write_bw (6) |
| 1238 | * put (6) into (1) we get |
| 1239 | * rate_(i+1) = rate_(i) (7) |
| 1240 | * |
| 1241 | * So we end up using (2) to always keep |
| 1242 | * rate_(i+1) ~= (write_bw / N) (8) |
| 1243 | * regardless of the value of pos_ratio. As long as (8) is satisfied, |
| 1244 | * pos_ratio is able to drive itself to 1.0, which is not only where |
| 1245 | * the dirty count meet the setpoint, but also where the slope of |
| 1246 | * pos_ratio is most flat and hence task_ratelimit is least fluctuated. |
| 1247 | */ |
| 1248 | balanced_dirty_ratelimit = div_u64((u64)task_ratelimit * write_bw, |
| 1249 | dirty_rate | 1); |
Wu Fengguang | bdaac49 | 2011-08-03 14:30:36 -0600 | [diff] [blame] | 1250 | /* |
| 1251 | * balanced_dirty_ratelimit ~= (write_bw / N) <= write_bw |
| 1252 | */ |
| 1253 | if (unlikely(balanced_dirty_ratelimit > write_bw)) |
| 1254 | balanced_dirty_ratelimit = write_bw; |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 1255 | |
Wu Fengguang | 7381131 | 2011-08-26 15:53:24 -0600 | [diff] [blame] | 1256 | /* |
| 1257 | * We could safely do this and return immediately: |
| 1258 | * |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1259 | * wb->dirty_ratelimit = balanced_dirty_ratelimit; |
Wu Fengguang | 7381131 | 2011-08-26 15:53:24 -0600 | [diff] [blame] | 1260 | * |
| 1261 | * However to get a more stable dirty_ratelimit, the below elaborated |
Wanpeng Li | 331cbde | 2012-06-09 11:10:55 +0800 | [diff] [blame] | 1262 | * code makes use of task_ratelimit to filter out singular points and |
Wu Fengguang | 7381131 | 2011-08-26 15:53:24 -0600 | [diff] [blame] | 1263 | * limit the step size. |
| 1264 | * |
| 1265 | * The below code essentially only uses the relative value of |
| 1266 | * |
| 1267 | * task_ratelimit - dirty_ratelimit |
| 1268 | * = (pos_ratio - 1) * dirty_ratelimit |
| 1269 | * |
| 1270 | * which reflects the direction and size of dirty position error. |
| 1271 | */ |
| 1272 | |
| 1273 | /* |
| 1274 | * dirty_ratelimit will follow balanced_dirty_ratelimit iff |
| 1275 | * task_ratelimit is on the same side of dirty_ratelimit, too. |
| 1276 | * For example, when |
| 1277 | * - dirty_ratelimit > balanced_dirty_ratelimit |
| 1278 | * - dirty_ratelimit > task_ratelimit (dirty pages are above setpoint) |
| 1279 | * lowering dirty_ratelimit will help meet both the position and rate |
| 1280 | * control targets. Otherwise, don't update dirty_ratelimit if it will |
| 1281 | * only help meet the rate target. After all, what the users ultimately |
| 1282 | * feel and care are stable dirty rate and small position error. |
| 1283 | * |
| 1284 | * |task_ratelimit - dirty_ratelimit| is used to limit the step size |
Wanpeng Li | 331cbde | 2012-06-09 11:10:55 +0800 | [diff] [blame] | 1285 | * and filter out the singular points of balanced_dirty_ratelimit. Which |
Wu Fengguang | 7381131 | 2011-08-26 15:53:24 -0600 | [diff] [blame] | 1286 | * keeps jumping around randomly and can even leap far away at times |
| 1287 | * due to the small 200ms estimation period of dirty_rate (we want to |
| 1288 | * keep that period small to reduce time lags). |
| 1289 | */ |
| 1290 | step = 0; |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1291 | |
| 1292 | /* |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1293 | * For strictlimit case, calculations above were based on wb counters |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1294 | * and limits (starting from pos_ratio = wb_position_ratio() and up to |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1295 | * balanced_dirty_ratelimit = task_ratelimit * write_bw / dirty_rate). |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1296 | * Hence, to calculate "step" properly, we have to use wb_dirty as |
| 1297 | * "dirty" and wb_setpoint as "setpoint". |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1298 | * |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1299 | * We rampup dirty_ratelimit forcibly if wb_dirty is low because |
| 1300 | * it's possible that wb_thresh is close to zero due to inactivity |
Tejun Heo | 970fb01 | 2015-05-22 18:23:24 -0400 | [diff] [blame] | 1301 | * of backing device. |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1302 | */ |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1303 | if (unlikely(wb->bdi->capabilities & BDI_CAP_STRICTLIMIT)) { |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1304 | dirty = dtc->wb_dirty; |
| 1305 | if (dtc->wb_dirty < 8) |
| 1306 | setpoint = dtc->wb_dirty + 1; |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1307 | else |
Tejun Heo | 970fb01 | 2015-05-22 18:23:24 -0400 | [diff] [blame] | 1308 | setpoint = (dtc->wb_thresh + dtc->wb_bg_thresh) / 2; |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1309 | } |
| 1310 | |
Wu Fengguang | 7381131 | 2011-08-26 15:53:24 -0600 | [diff] [blame] | 1311 | if (dirty < setpoint) { |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1312 | x = min3(wb->balanced_dirty_ratelimit, |
Mark Rustad | 7c80996 | 2014-10-09 15:28:15 -0700 | [diff] [blame] | 1313 | balanced_dirty_ratelimit, task_ratelimit); |
Wu Fengguang | 7381131 | 2011-08-26 15:53:24 -0600 | [diff] [blame] | 1314 | if (dirty_ratelimit < x) |
| 1315 | step = x - dirty_ratelimit; |
| 1316 | } else { |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1317 | x = max3(wb->balanced_dirty_ratelimit, |
Mark Rustad | 7c80996 | 2014-10-09 15:28:15 -0700 | [diff] [blame] | 1318 | balanced_dirty_ratelimit, task_ratelimit); |
Wu Fengguang | 7381131 | 2011-08-26 15:53:24 -0600 | [diff] [blame] | 1319 | if (dirty_ratelimit > x) |
| 1320 | step = dirty_ratelimit - x; |
| 1321 | } |
| 1322 | |
| 1323 | /* |
| 1324 | * Don't pursue 100% rate matching. It's impossible since the balanced |
| 1325 | * rate itself is constantly fluctuating. So decrease the track speed |
| 1326 | * when it gets close to the target. Helps eliminate pointless tremors. |
| 1327 | */ |
Andrey Ryabinin | d59b108 | 2016-03-15 14:55:27 -0700 | [diff] [blame] | 1328 | shift = dirty_ratelimit / (2 * step + 1); |
| 1329 | if (shift < BITS_PER_LONG) |
| 1330 | step = DIV_ROUND_UP(step >> shift, 8); |
| 1331 | else |
| 1332 | step = 0; |
Wu Fengguang | 7381131 | 2011-08-26 15:53:24 -0600 | [diff] [blame] | 1333 | |
| 1334 | if (dirty_ratelimit < balanced_dirty_ratelimit) |
| 1335 | dirty_ratelimit += step; |
| 1336 | else |
| 1337 | dirty_ratelimit -= step; |
| 1338 | |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1339 | wb->dirty_ratelimit = max(dirty_ratelimit, 1UL); |
| 1340 | wb->balanced_dirty_ratelimit = balanced_dirty_ratelimit; |
Wu Fengguang | b48c104 | 2011-03-02 17:22:49 -0600 | [diff] [blame] | 1341 | |
Tejun Heo | 5634cc2 | 2015-08-18 14:54:56 -0700 | [diff] [blame] | 1342 | trace_bdi_dirty_ratelimit(wb, dirty_rate, task_ratelimit); |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 1343 | } |
| 1344 | |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1345 | static void __wb_update_bandwidth(struct dirty_throttle_control *gdtc, |
| 1346 | struct dirty_throttle_control *mdtc, |
Tejun Heo | 8a73179 | 2015-05-22 18:23:20 -0400 | [diff] [blame] | 1347 | unsigned long start_time, |
| 1348 | bool update_ratelimit) |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1349 | { |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1350 | struct bdi_writeback *wb = gdtc->wb; |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1351 | unsigned long now = jiffies; |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1352 | unsigned long elapsed = now - wb->bw_time_stamp; |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 1353 | unsigned long dirtied; |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1354 | unsigned long written; |
| 1355 | |
Tejun Heo | 8a73179 | 2015-05-22 18:23:20 -0400 | [diff] [blame] | 1356 | lockdep_assert_held(&wb->list_lock); |
| 1357 | |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1358 | /* |
| 1359 | * rate-limit, only update once every 200ms. |
| 1360 | */ |
| 1361 | if (elapsed < BANDWIDTH_INTERVAL) |
| 1362 | return; |
| 1363 | |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1364 | dirtied = percpu_counter_read(&wb->stat[WB_DIRTIED]); |
| 1365 | written = percpu_counter_read(&wb->stat[WB_WRITTEN]); |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1366 | |
| 1367 | /* |
| 1368 | * Skip quiet periods when disk bandwidth is under-utilized. |
| 1369 | * (at least 1s idle time between two flusher runs) |
| 1370 | */ |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1371 | if (elapsed > HZ && time_before(wb->bw_time_stamp, start_time)) |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1372 | goto snapshot; |
| 1373 | |
Tejun Heo | 8a73179 | 2015-05-22 18:23:20 -0400 | [diff] [blame] | 1374 | if (update_ratelimit) { |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1375 | domain_update_bandwidth(gdtc, now); |
| 1376 | wb_update_dirty_ratelimit(gdtc, dirtied, elapsed); |
| 1377 | |
| 1378 | /* |
| 1379 | * @mdtc is always NULL if !CGROUP_WRITEBACK but the |
| 1380 | * compiler has no way to figure that out. Help it. |
| 1381 | */ |
| 1382 | if (IS_ENABLED(CONFIG_CGROUP_WRITEBACK) && mdtc) { |
| 1383 | domain_update_bandwidth(mdtc, now); |
| 1384 | wb_update_dirty_ratelimit(mdtc, dirtied, elapsed); |
| 1385 | } |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 1386 | } |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1387 | wb_update_write_bandwidth(wb, elapsed, written); |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1388 | |
| 1389 | snapshot: |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1390 | wb->dirtied_stamp = dirtied; |
| 1391 | wb->written_stamp = written; |
| 1392 | wb->bw_time_stamp = now; |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1393 | } |
| 1394 | |
Tejun Heo | 8a73179 | 2015-05-22 18:23:20 -0400 | [diff] [blame] | 1395 | void wb_update_bandwidth(struct bdi_writeback *wb, unsigned long start_time) |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1396 | { |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1397 | struct dirty_throttle_control gdtc = { GDTC_INIT(wb) }; |
| 1398 | |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1399 | __wb_update_bandwidth(&gdtc, NULL, start_time, false); |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1400 | } |
| 1401 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1402 | /* |
Namjae Jeon | d0e1d66 | 2012-12-11 16:00:21 -0800 | [diff] [blame] | 1403 | * After a task dirtied this many pages, balance_dirty_pages_ratelimited() |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1404 | * will look to see if it needs to start dirty throttling. |
| 1405 | * |
| 1406 | * If dirty_poll_interval is too low, big NUMA machines will call the expensive |
Michal Hocko | c41f012 | 2017-09-06 16:23:36 -0700 | [diff] [blame] | 1407 | * global_zone_page_state() too often. So scale it near-sqrt to the safety margin |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1408 | * (the number of pages we may dirty without exceeding the dirty limits). |
| 1409 | */ |
| 1410 | static unsigned long dirty_poll_interval(unsigned long dirty, |
| 1411 | unsigned long thresh) |
| 1412 | { |
| 1413 | if (thresh > dirty) |
| 1414 | return 1UL << (ilog2(thresh - dirty) >> 1); |
| 1415 | |
| 1416 | return 1; |
| 1417 | } |
| 1418 | |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1419 | static unsigned long wb_max_pause(struct bdi_writeback *wb, |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1420 | unsigned long wb_dirty) |
Wu Fengguang | c8462cc | 2011-06-11 19:21:43 -0600 | [diff] [blame] | 1421 | { |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1422 | unsigned long bw = wb->avg_write_bandwidth; |
Fengguang Wu | e3b6c65 | 2013-10-16 13:47:03 -0700 | [diff] [blame] | 1423 | unsigned long t; |
Wu Fengguang | c8462cc | 2011-06-11 19:21:43 -0600 | [diff] [blame] | 1424 | |
| 1425 | /* |
| 1426 | * Limit pause time for small memory systems. If sleeping for too long |
| 1427 | * time, a small pool of dirty/writeback pages may go empty and disk go |
| 1428 | * idle. |
| 1429 | * |
| 1430 | * 8 serves as the safety ratio. |
| 1431 | */ |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1432 | t = wb_dirty / (1 + bw / roundup_pow_of_two(1 + HZ / 8)); |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1433 | t++; |
| 1434 | |
Fengguang Wu | e3b6c65 | 2013-10-16 13:47:03 -0700 | [diff] [blame] | 1435 | return min_t(unsigned long, t, MAX_PAUSE); |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1436 | } |
| 1437 | |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1438 | static long wb_min_pause(struct bdi_writeback *wb, |
| 1439 | long max_pause, |
| 1440 | unsigned long task_ratelimit, |
| 1441 | unsigned long dirty_ratelimit, |
| 1442 | int *nr_dirtied_pause) |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1443 | { |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1444 | long hi = ilog2(wb->avg_write_bandwidth); |
| 1445 | long lo = ilog2(wb->dirty_ratelimit); |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1446 | long t; /* target pause */ |
| 1447 | long pause; /* estimated next pause */ |
| 1448 | int pages; /* target nr_dirtied_pause */ |
| 1449 | |
| 1450 | /* target for 10ms pause on 1-dd case */ |
| 1451 | t = max(1, HZ / 100); |
Wu Fengguang | c8462cc | 2011-06-11 19:21:43 -0600 | [diff] [blame] | 1452 | |
| 1453 | /* |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1454 | * Scale up pause time for concurrent dirtiers in order to reduce CPU |
| 1455 | * overheads. |
| 1456 | * |
| 1457 | * (N * 10ms) on 2^N concurrent tasks. |
Wu Fengguang | c8462cc | 2011-06-11 19:21:43 -0600 | [diff] [blame] | 1458 | */ |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1459 | if (hi > lo) |
| 1460 | t += (hi - lo) * (10 * HZ) / 1024; |
| 1461 | |
| 1462 | /* |
| 1463 | * This is a bit convoluted. We try to base the next nr_dirtied_pause |
| 1464 | * on the much more stable dirty_ratelimit. However the next pause time |
| 1465 | * will be computed based on task_ratelimit and the two rate limits may |
| 1466 | * depart considerably at some time. Especially if task_ratelimit goes |
| 1467 | * below dirty_ratelimit/2 and the target pause is max_pause, the next |
| 1468 | * pause time will be max_pause*2 _trimmed down_ to max_pause. As a |
| 1469 | * result task_ratelimit won't be executed faithfully, which could |
| 1470 | * eventually bring down dirty_ratelimit. |
| 1471 | * |
| 1472 | * We apply two rules to fix it up: |
| 1473 | * 1) try to estimate the next pause time and if necessary, use a lower |
| 1474 | * nr_dirtied_pause so as not to exceed max_pause. When this happens, |
| 1475 | * nr_dirtied_pause will be "dancing" with task_ratelimit. |
| 1476 | * 2) limit the target pause time to max_pause/2, so that the normal |
| 1477 | * small fluctuations of task_ratelimit won't trigger rule (1) and |
| 1478 | * nr_dirtied_pause will remain as stable as dirty_ratelimit. |
| 1479 | */ |
| 1480 | t = min(t, 1 + max_pause / 2); |
| 1481 | pages = dirty_ratelimit * t / roundup_pow_of_two(HZ); |
| 1482 | |
Wu Fengguang | 5b9b357 | 2011-12-06 13:17:17 -0600 | [diff] [blame] | 1483 | /* |
| 1484 | * Tiny nr_dirtied_pause is found to hurt I/O performance in the test |
| 1485 | * case fio-mmap-randwrite-64k, which does 16*{sync read, async write}. |
| 1486 | * When the 16 consecutive reads are often interrupted by some dirty |
| 1487 | * throttling pause during the async writes, cfq will go into idles |
| 1488 | * (deadline is fine). So push nr_dirtied_pause as high as possible |
| 1489 | * until reaches DIRTY_POLL_THRESH=32 pages. |
| 1490 | */ |
| 1491 | if (pages < DIRTY_POLL_THRESH) { |
| 1492 | t = max_pause; |
| 1493 | pages = dirty_ratelimit * t / roundup_pow_of_two(HZ); |
| 1494 | if (pages > DIRTY_POLL_THRESH) { |
| 1495 | pages = DIRTY_POLL_THRESH; |
| 1496 | t = HZ * DIRTY_POLL_THRESH / dirty_ratelimit; |
| 1497 | } |
| 1498 | } |
| 1499 | |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1500 | pause = HZ * pages / (task_ratelimit + 1); |
| 1501 | if (pause > max_pause) { |
| 1502 | t = max_pause; |
| 1503 | pages = task_ratelimit * t / roundup_pow_of_two(HZ); |
| 1504 | } |
| 1505 | |
| 1506 | *nr_dirtied_pause = pages; |
| 1507 | /* |
| 1508 | * The minimal pause time will normally be half the target pause time. |
| 1509 | */ |
Wu Fengguang | 5b9b357 | 2011-12-06 13:17:17 -0600 | [diff] [blame] | 1510 | return pages >= DIRTY_POLL_THRESH ? 1 + t / 2 : t; |
Wu Fengguang | c8462cc | 2011-06-11 19:21:43 -0600 | [diff] [blame] | 1511 | } |
| 1512 | |
Tejun Heo | 970fb01 | 2015-05-22 18:23:24 -0400 | [diff] [blame] | 1513 | static inline void wb_dirty_limits(struct dirty_throttle_control *dtc) |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1514 | { |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1515 | struct bdi_writeback *wb = dtc->wb; |
Tejun Heo | 93f78d8 | 2015-05-22 17:13:27 -0400 | [diff] [blame] | 1516 | unsigned long wb_reclaimable; |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1517 | |
| 1518 | /* |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1519 | * wb_thresh is not treated as some limiting factor as |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1520 | * dirty_thresh, due to reasons |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1521 | * - in JBOD setup, wb_thresh can fluctuate a lot |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1522 | * - in a system with HDD and USB key, the USB key may somehow |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1523 | * go into state (wb_dirty >> wb_thresh) either because |
| 1524 | * wb_dirty starts high, or because wb_thresh drops low. |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1525 | * In this case we don't want to hard throttle the USB key |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1526 | * dirtiers for 100 seconds until wb_dirty drops under |
| 1527 | * wb_thresh. Instead the auxiliary wb control line in |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1528 | * wb_position_ratio() will let the dirtier task progress |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1529 | * at some rate <= (write_bw / 2) for bringing down wb_dirty. |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1530 | */ |
Tejun Heo | b1cbc6d | 2015-05-22 18:23:25 -0400 | [diff] [blame] | 1531 | dtc->wb_thresh = __wb_calc_thresh(dtc); |
Tejun Heo | 970fb01 | 2015-05-22 18:23:24 -0400 | [diff] [blame] | 1532 | dtc->wb_bg_thresh = dtc->thresh ? |
| 1533 | div_u64((u64)dtc->wb_thresh * dtc->bg_thresh, dtc->thresh) : 0; |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1534 | |
| 1535 | /* |
| 1536 | * In order to avoid the stacked BDI deadlock we need |
| 1537 | * to ensure we accurately count the 'dirty' pages when |
| 1538 | * the threshold is low. |
| 1539 | * |
| 1540 | * Otherwise it would be possible to get thresh+n pages |
| 1541 | * reported dirty, even though there are thresh-m pages |
| 1542 | * actually dirty; with m+n sitting in the percpu |
| 1543 | * deltas. |
| 1544 | */ |
Wang Long | 2bce774 | 2017-11-15 17:39:03 -0800 | [diff] [blame] | 1545 | if (dtc->wb_thresh < 2 * wb_stat_error()) { |
Tejun Heo | 93f78d8 | 2015-05-22 17:13:27 -0400 | [diff] [blame] | 1546 | wb_reclaimable = wb_stat_sum(wb, WB_RECLAIMABLE); |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1547 | dtc->wb_dirty = wb_reclaimable + wb_stat_sum(wb, WB_WRITEBACK); |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1548 | } else { |
Tejun Heo | 93f78d8 | 2015-05-22 17:13:27 -0400 | [diff] [blame] | 1549 | wb_reclaimable = wb_stat(wb, WB_RECLAIMABLE); |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1550 | dtc->wb_dirty = wb_reclaimable + wb_stat(wb, WB_WRITEBACK); |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1551 | } |
| 1552 | } |
| 1553 | |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1554 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1555 | * balance_dirty_pages() must be called by processes which are generating dirty |
| 1556 | * data. It looks at the number of dirty pages in the machine and will force |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1557 | * the caller to wait once crossing the (background_thresh + dirty_thresh) / 2. |
Jens Axboe | 5b0830c | 2009-09-23 19:37:09 +0200 | [diff] [blame] | 1558 | * If we're over `background_thresh' then the writeback threads are woken to |
| 1559 | * perform some writeout. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1560 | */ |
Tahsin Erdogan | 4c578dc | 2017-11-15 17:33:19 -0800 | [diff] [blame] | 1561 | static void balance_dirty_pages(struct bdi_writeback *wb, |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1562 | unsigned long pages_dirtied) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1563 | { |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1564 | struct dirty_throttle_control gdtc_stor = { GDTC_INIT(wb) }; |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1565 | struct dirty_throttle_control mdtc_stor = { MDTC_INIT(wb, &gdtc_stor) }; |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1566 | struct dirty_throttle_control * const gdtc = &gdtc_stor; |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1567 | struct dirty_throttle_control * const mdtc = mdtc_valid(&mdtc_stor) ? |
| 1568 | &mdtc_stor : NULL; |
| 1569 | struct dirty_throttle_control *sdtc; |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1570 | unsigned long nr_reclaimable; /* = file_dirty + unstable_nfs */ |
Wu Fengguang | 8371235 | 2011-06-11 19:25:42 -0600 | [diff] [blame] | 1571 | long period; |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1572 | long pause; |
| 1573 | long max_pause; |
| 1574 | long min_pause; |
| 1575 | int nr_dirtied_pause; |
Wu Fengguang | e50e372 | 2010-08-11 14:17:37 -0700 | [diff] [blame] | 1576 | bool dirty_exceeded = false; |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1577 | unsigned long task_ratelimit; |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1578 | unsigned long dirty_ratelimit; |
Tejun Heo | dfb8ae5 | 2015-05-22 17:13:40 -0400 | [diff] [blame] | 1579 | struct backing_dev_info *bdi = wb->bdi; |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1580 | bool strictlimit = bdi->capabilities & BDI_CAP_STRICTLIMIT; |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1581 | unsigned long start_time = jiffies; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1582 | |
| 1583 | for (;;) { |
Wu Fengguang | 8371235 | 2011-06-11 19:25:42 -0600 | [diff] [blame] | 1584 | unsigned long now = jiffies; |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1585 | unsigned long dirty, thresh, bg_thresh; |
Yang Shi | 50e55bf | 2015-11-20 15:57:10 -0800 | [diff] [blame] | 1586 | unsigned long m_dirty = 0; /* stop bogus uninit warnings */ |
| 1587 | unsigned long m_thresh = 0; |
| 1588 | unsigned long m_bg_thresh = 0; |
Wu Fengguang | 8371235 | 2011-06-11 19:25:42 -0600 | [diff] [blame] | 1589 | |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1590 | /* |
| 1591 | * Unstable writes are a feature of certain networked |
| 1592 | * filesystems (i.e. NFS) in which data may have been |
| 1593 | * written to the server's write cache, but has not yet |
| 1594 | * been flushed to permanent storage. |
| 1595 | */ |
Mel Gorman | 11fb998 | 2016-07-28 15:46:20 -0700 | [diff] [blame] | 1596 | nr_reclaimable = global_node_page_state(NR_FILE_DIRTY) + |
| 1597 | global_node_page_state(NR_UNSTABLE_NFS); |
Tejun Heo | 9fc3a43 | 2015-05-22 18:23:30 -0400 | [diff] [blame] | 1598 | gdtc->avail = global_dirtyable_memory(); |
Mel Gorman | 11fb998 | 2016-07-28 15:46:20 -0700 | [diff] [blame] | 1599 | gdtc->dirty = nr_reclaimable + global_node_page_state(NR_WRITEBACK); |
Peter Zijlstra | 5fce25a | 2007-11-14 16:59:15 -0800 | [diff] [blame] | 1600 | |
Tejun Heo | 9fc3a43 | 2015-05-22 18:23:30 -0400 | [diff] [blame] | 1601 | domain_dirty_limits(gdtc); |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 1602 | |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1603 | if (unlikely(strictlimit)) { |
Tejun Heo | 970fb01 | 2015-05-22 18:23:24 -0400 | [diff] [blame] | 1604 | wb_dirty_limits(gdtc); |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1605 | |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1606 | dirty = gdtc->wb_dirty; |
| 1607 | thresh = gdtc->wb_thresh; |
Tejun Heo | 970fb01 | 2015-05-22 18:23:24 -0400 | [diff] [blame] | 1608 | bg_thresh = gdtc->wb_bg_thresh; |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1609 | } else { |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1610 | dirty = gdtc->dirty; |
| 1611 | thresh = gdtc->thresh; |
| 1612 | bg_thresh = gdtc->bg_thresh; |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1613 | } |
| 1614 | |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1615 | if (mdtc) { |
Tejun Heo | c5edf9c | 2015-09-29 13:04:26 -0400 | [diff] [blame] | 1616 | unsigned long filepages, headroom, writeback; |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1617 | |
| 1618 | /* |
| 1619 | * If @wb belongs to !root memcg, repeat the same |
| 1620 | * basic calculations for the memcg domain. |
| 1621 | */ |
Tejun Heo | c5edf9c | 2015-09-29 13:04:26 -0400 | [diff] [blame] | 1622 | mem_cgroup_wb_stats(wb, &filepages, &headroom, |
| 1623 | &mdtc->dirty, &writeback); |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1624 | mdtc->dirty += writeback; |
Tejun Heo | c5edf9c | 2015-09-29 13:04:26 -0400 | [diff] [blame] | 1625 | mdtc_calc_avail(mdtc, filepages, headroom); |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1626 | |
| 1627 | domain_dirty_limits(mdtc); |
| 1628 | |
| 1629 | if (unlikely(strictlimit)) { |
| 1630 | wb_dirty_limits(mdtc); |
| 1631 | m_dirty = mdtc->wb_dirty; |
| 1632 | m_thresh = mdtc->wb_thresh; |
| 1633 | m_bg_thresh = mdtc->wb_bg_thresh; |
| 1634 | } else { |
| 1635 | m_dirty = mdtc->dirty; |
| 1636 | m_thresh = mdtc->thresh; |
| 1637 | m_bg_thresh = mdtc->bg_thresh; |
| 1638 | } |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 1639 | } |
| 1640 | |
| 1641 | /* |
| 1642 | * Throttle it only when the background writeback cannot |
| 1643 | * catch-up. This avoids (excessively) small writeouts |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1644 | * when the wb limits are ramping up in case of !strictlimit. |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1645 | * |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1646 | * In strictlimit case make decision based on the wb counters |
| 1647 | * and limits. Small writeouts when the wb limits are ramping |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1648 | * up are the price we consciously pay for strictlimit-ing. |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1649 | * |
| 1650 | * If memcg domain is in effect, @dirty should be under |
| 1651 | * both global and memcg freerun ceilings. |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 1652 | */ |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1653 | if (dirty <= dirty_freerun_ceiling(thresh, bg_thresh) && |
| 1654 | (!mdtc || |
| 1655 | m_dirty <= dirty_freerun_ceiling(m_thresh, m_bg_thresh))) { |
| 1656 | unsigned long intv = dirty_poll_interval(dirty, thresh); |
| 1657 | unsigned long m_intv = ULONG_MAX; |
| 1658 | |
Wu Fengguang | 8371235 | 2011-06-11 19:25:42 -0600 | [diff] [blame] | 1659 | current->dirty_paused_when = now; |
| 1660 | current->nr_dirtied = 0; |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1661 | if (mdtc) |
| 1662 | m_intv = dirty_poll_interval(m_dirty, m_thresh); |
| 1663 | current->nr_dirtied_pause = min(intv, m_intv); |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 1664 | break; |
Wu Fengguang | 8371235 | 2011-06-11 19:25:42 -0600 | [diff] [blame] | 1665 | } |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 1666 | |
Tejun Heo | bc05873 | 2015-05-22 17:13:53 -0400 | [diff] [blame] | 1667 | if (unlikely(!writeback_in_progress(wb))) |
Tejun Heo | 9ecf4866 | 2015-05-22 17:13:54 -0400 | [diff] [blame] | 1668 | wb_start_background_writeback(wb); |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1669 | |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1670 | /* |
| 1671 | * Calculate global domain's pos_ratio and select the |
| 1672 | * global dtc by default. |
| 1673 | */ |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1674 | if (!strictlimit) |
Tejun Heo | 970fb01 | 2015-05-22 18:23:24 -0400 | [diff] [blame] | 1675 | wb_dirty_limits(gdtc); |
Peter Zijlstra | 5fce25a | 2007-11-14 16:59:15 -0800 | [diff] [blame] | 1676 | |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1677 | dirty_exceeded = (gdtc->wb_dirty > gdtc->wb_thresh) && |
| 1678 | ((gdtc->dirty > gdtc->thresh) || strictlimit); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1679 | |
Tejun Heo | daddfa3 | 2015-05-22 18:23:26 -0400 | [diff] [blame] | 1680 | wb_position_ratio(gdtc); |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1681 | sdtc = gdtc; |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1682 | |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1683 | if (mdtc) { |
| 1684 | /* |
| 1685 | * If memcg domain is in effect, calculate its |
| 1686 | * pos_ratio. @wb should satisfy constraints from |
| 1687 | * both global and memcg domains. Choose the one |
| 1688 | * w/ lower pos_ratio. |
| 1689 | */ |
| 1690 | if (!strictlimit) |
| 1691 | wb_dirty_limits(mdtc); |
| 1692 | |
| 1693 | dirty_exceeded |= (mdtc->wb_dirty > mdtc->wb_thresh) && |
| 1694 | ((mdtc->dirty > mdtc->thresh) || strictlimit); |
| 1695 | |
| 1696 | wb_position_ratio(mdtc); |
| 1697 | if (mdtc->pos_ratio < gdtc->pos_ratio) |
| 1698 | sdtc = mdtc; |
| 1699 | } |
Tejun Heo | daddfa3 | 2015-05-22 18:23:26 -0400 | [diff] [blame] | 1700 | |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1701 | if (dirty_exceeded && !wb->dirty_exceeded) |
| 1702 | wb->dirty_exceeded = 1; |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 1703 | |
Tejun Heo | 8a73179 | 2015-05-22 18:23:20 -0400 | [diff] [blame] | 1704 | if (time_is_before_jiffies(wb->bw_time_stamp + |
| 1705 | BANDWIDTH_INTERVAL)) { |
| 1706 | spin_lock(&wb->list_lock); |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1707 | __wb_update_bandwidth(gdtc, mdtc, start_time, true); |
Tejun Heo | 8a73179 | 2015-05-22 18:23:20 -0400 | [diff] [blame] | 1708 | spin_unlock(&wb->list_lock); |
| 1709 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1710 | |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1711 | /* throttle according to the chosen dtc */ |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1712 | dirty_ratelimit = wb->dirty_ratelimit; |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1713 | task_ratelimit = ((u64)dirty_ratelimit * sdtc->pos_ratio) >> |
Wu Fengguang | 3a73dbb | 2011-11-07 19:19:28 +0800 | [diff] [blame] | 1714 | RATELIMIT_CALC_SHIFT; |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1715 | max_pause = wb_max_pause(wb, sdtc->wb_dirty); |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1716 | min_pause = wb_min_pause(wb, max_pause, |
| 1717 | task_ratelimit, dirty_ratelimit, |
| 1718 | &nr_dirtied_pause); |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1719 | |
Wu Fengguang | 3a73dbb | 2011-11-07 19:19:28 +0800 | [diff] [blame] | 1720 | if (unlikely(task_ratelimit == 0)) { |
Wu Fengguang | 8371235 | 2011-06-11 19:25:42 -0600 | [diff] [blame] | 1721 | period = max_pause; |
Wu Fengguang | c8462cc | 2011-06-11 19:21:43 -0600 | [diff] [blame] | 1722 | pause = max_pause; |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1723 | goto pause; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1724 | } |
Wu Fengguang | 8371235 | 2011-06-11 19:25:42 -0600 | [diff] [blame] | 1725 | period = HZ * pages_dirtied / task_ratelimit; |
| 1726 | pause = period; |
| 1727 | if (current->dirty_paused_when) |
| 1728 | pause -= now - current->dirty_paused_when; |
| 1729 | /* |
| 1730 | * For less than 1s think time (ext3/4 may block the dirtier |
| 1731 | * for up to 800ms from time to time on 1-HDD; so does xfs, |
| 1732 | * however at much less frequency), try to compensate it in |
| 1733 | * future periods by updating the virtual time; otherwise just |
| 1734 | * do a reset, as it may be a light dirtier. |
| 1735 | */ |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1736 | if (pause < min_pause) { |
Tejun Heo | 5634cc2 | 2015-08-18 14:54:56 -0700 | [diff] [blame] | 1737 | trace_balance_dirty_pages(wb, |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1738 | sdtc->thresh, |
| 1739 | sdtc->bg_thresh, |
| 1740 | sdtc->dirty, |
| 1741 | sdtc->wb_thresh, |
| 1742 | sdtc->wb_dirty, |
Wu Fengguang | ece13ac | 2010-08-29 23:33:20 -0600 | [diff] [blame] | 1743 | dirty_ratelimit, |
| 1744 | task_ratelimit, |
| 1745 | pages_dirtied, |
Wu Fengguang | 8371235 | 2011-06-11 19:25:42 -0600 | [diff] [blame] | 1746 | period, |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1747 | min(pause, 0L), |
Wu Fengguang | ece13ac | 2010-08-29 23:33:20 -0600 | [diff] [blame] | 1748 | start_time); |
Wu Fengguang | 8371235 | 2011-06-11 19:25:42 -0600 | [diff] [blame] | 1749 | if (pause < -HZ) { |
| 1750 | current->dirty_paused_when = now; |
| 1751 | current->nr_dirtied = 0; |
| 1752 | } else if (period) { |
| 1753 | current->dirty_paused_when += period; |
| 1754 | current->nr_dirtied = 0; |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1755 | } else if (current->nr_dirtied_pause <= pages_dirtied) |
| 1756 | current->nr_dirtied_pause += pages_dirtied; |
Wu Fengguang | 57fc978 | 2011-06-11 19:32:32 -0600 | [diff] [blame] | 1757 | break; |
| 1758 | } |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1759 | if (unlikely(pause > max_pause)) { |
| 1760 | /* for occasional dropped task_ratelimit */ |
| 1761 | now += min(pause - max_pause, max_pause); |
| 1762 | pause = max_pause; |
| 1763 | } |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1764 | |
| 1765 | pause: |
Tejun Heo | 5634cc2 | 2015-08-18 14:54:56 -0700 | [diff] [blame] | 1766 | trace_balance_dirty_pages(wb, |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1767 | sdtc->thresh, |
| 1768 | sdtc->bg_thresh, |
| 1769 | sdtc->dirty, |
| 1770 | sdtc->wb_thresh, |
| 1771 | sdtc->wb_dirty, |
Wu Fengguang | ece13ac | 2010-08-29 23:33:20 -0600 | [diff] [blame] | 1772 | dirty_ratelimit, |
| 1773 | task_ratelimit, |
| 1774 | pages_dirtied, |
Wu Fengguang | 8371235 | 2011-06-11 19:25:42 -0600 | [diff] [blame] | 1775 | period, |
Wu Fengguang | ece13ac | 2010-08-29 23:33:20 -0600 | [diff] [blame] | 1776 | pause, |
| 1777 | start_time); |
Jan Kara | 499d05e | 2011-11-16 19:34:48 +0800 | [diff] [blame] | 1778 | __set_current_state(TASK_KILLABLE); |
Jens Axboe | b57d74a | 2016-09-01 10:20:33 -0600 | [diff] [blame] | 1779 | wb->dirty_sleep = now; |
Wu Fengguang | d25105e | 2009-10-09 12:40:42 +0200 | [diff] [blame] | 1780 | io_schedule_timeout(pause); |
Jens Axboe | 87c6a9b | 2009-09-17 19:59:14 +0200 | [diff] [blame] | 1781 | |
Wu Fengguang | 8371235 | 2011-06-11 19:25:42 -0600 | [diff] [blame] | 1782 | current->dirty_paused_when = now + pause; |
| 1783 | current->nr_dirtied = 0; |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1784 | current->nr_dirtied_pause = nr_dirtied_pause; |
Wu Fengguang | 8371235 | 2011-06-11 19:25:42 -0600 | [diff] [blame] | 1785 | |
Wu Fengguang | ffd1f60 | 2011-06-19 22:18:42 -0600 | [diff] [blame] | 1786 | /* |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1787 | * This is typically equal to (dirty < thresh) and can also |
| 1788 | * keep "1000+ dd on a slow USB stick" under control. |
Wu Fengguang | ffd1f60 | 2011-06-19 22:18:42 -0600 | [diff] [blame] | 1789 | */ |
Wu Fengguang | 1df6471 | 2011-11-13 19:47:32 -0600 | [diff] [blame] | 1790 | if (task_ratelimit) |
Wu Fengguang | ffd1f60 | 2011-06-19 22:18:42 -0600 | [diff] [blame] | 1791 | break; |
Jan Kara | 499d05e | 2011-11-16 19:34:48 +0800 | [diff] [blame] | 1792 | |
Wu Fengguang | c5c6343 | 2011-12-02 10:21:33 -0600 | [diff] [blame] | 1793 | /* |
| 1794 | * In the case of an unresponding NFS server and the NFS dirty |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1795 | * pages exceeds dirty_thresh, give the other good wb's a pipe |
Wu Fengguang | c5c6343 | 2011-12-02 10:21:33 -0600 | [diff] [blame] | 1796 | * to go through, so that tasks on them still remain responsive. |
| 1797 | * |
Masahiro Yamada | 3f8b6fb | 2017-02-27 14:29:25 -0800 | [diff] [blame] | 1798 | * In theory 1 page is enough to keep the consumer-producer |
Wu Fengguang | c5c6343 | 2011-12-02 10:21:33 -0600 | [diff] [blame] | 1799 | * pipe going: the flusher cleans 1 page => the task dirties 1 |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1800 | * more page. However wb_dirty has accounting errors. So use |
Tejun Heo | 93f78d8 | 2015-05-22 17:13:27 -0400 | [diff] [blame] | 1801 | * the larger and more IO friendly wb_stat_error. |
Wu Fengguang | c5c6343 | 2011-12-02 10:21:33 -0600 | [diff] [blame] | 1802 | */ |
Wang Long | 2bce774 | 2017-11-15 17:39:03 -0800 | [diff] [blame] | 1803 | if (sdtc->wb_dirty <= wb_stat_error()) |
Wu Fengguang | c5c6343 | 2011-12-02 10:21:33 -0600 | [diff] [blame] | 1804 | break; |
| 1805 | |
Jan Kara | 499d05e | 2011-11-16 19:34:48 +0800 | [diff] [blame] | 1806 | if (fatal_signal_pending(current)) |
| 1807 | break; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1808 | } |
| 1809 | |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1810 | if (!dirty_exceeded && wb->dirty_exceeded) |
| 1811 | wb->dirty_exceeded = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1812 | |
Tejun Heo | bc05873 | 2015-05-22 17:13:53 -0400 | [diff] [blame] | 1813 | if (writeback_in_progress(wb)) |
Jens Axboe | 5b0830c | 2009-09-23 19:37:09 +0200 | [diff] [blame] | 1814 | return; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1815 | |
| 1816 | /* |
| 1817 | * In laptop mode, we wait until hitting the higher threshold before |
| 1818 | * starting background writeout, and then write out all the way down |
| 1819 | * to the lower threshold. So slow writers cause minimal disk activity. |
| 1820 | * |
| 1821 | * In normal mode, we start background writeout at the lower |
| 1822 | * background_thresh, to keep the amount of dirty memory low. |
| 1823 | */ |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1824 | if (laptop_mode) |
| 1825 | return; |
| 1826 | |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1827 | if (nr_reclaimable > gdtc->bg_thresh) |
Tejun Heo | 9ecf4866 | 2015-05-22 17:13:54 -0400 | [diff] [blame] | 1828 | wb_start_background_writeback(wb); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1829 | } |
| 1830 | |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1831 | static DEFINE_PER_CPU(int, bdp_ratelimits); |
Tejun Heo | 245b2e7 | 2009-06-24 15:13:48 +0900 | [diff] [blame] | 1832 | |
Wu Fengguang | 54848d7 | 2011-04-05 13:21:19 -0600 | [diff] [blame] | 1833 | /* |
| 1834 | * Normal tasks are throttled by |
| 1835 | * loop { |
| 1836 | * dirty tsk->nr_dirtied_pause pages; |
| 1837 | * take a snap in balance_dirty_pages(); |
| 1838 | * } |
| 1839 | * However there is a worst case. If every task exit immediately when dirtied |
| 1840 | * (tsk->nr_dirtied_pause - 1) pages, balance_dirty_pages() will never be |
| 1841 | * called to throttle the page dirties. The solution is to save the not yet |
| 1842 | * throttled page dirties in dirty_throttle_leaks on task exit and charge them |
| 1843 | * randomly into the running tasks. This works well for the above worst case, |
| 1844 | * as the new task will pick up and accumulate the old task's leaked dirty |
| 1845 | * count and eventually get throttled. |
| 1846 | */ |
| 1847 | DEFINE_PER_CPU(int, dirty_throttle_leaks) = 0; |
| 1848 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1849 | /** |
Namjae Jeon | d0e1d66 | 2012-12-11 16:00:21 -0800 | [diff] [blame] | 1850 | * balance_dirty_pages_ratelimited - balance dirty memory state |
Martin Waitz | 67be2dd | 2005-05-01 08:59:26 -0700 | [diff] [blame] | 1851 | * @mapping: address_space which was dirtied |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1852 | * |
| 1853 | * Processes which are dirtying memory should call in here once for each page |
| 1854 | * which was newly dirtied. The function will periodically check the system's |
| 1855 | * dirty state and will initiate writeback if needed. |
| 1856 | * |
| 1857 | * On really big machines, get_writeback_state is expensive, so try to avoid |
| 1858 | * calling it too often (ratelimiting). But once we're over the dirty memory |
| 1859 | * limit we decrease the ratelimiting by a lot, to prevent individual processes |
| 1860 | * from overshooting the limit by (ratelimit_pages) each. |
| 1861 | */ |
Namjae Jeon | d0e1d66 | 2012-12-11 16:00:21 -0800 | [diff] [blame] | 1862 | void balance_dirty_pages_ratelimited(struct address_space *mapping) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1863 | { |
Tejun Heo | dfb8ae5 | 2015-05-22 17:13:40 -0400 | [diff] [blame] | 1864 | struct inode *inode = mapping->host; |
| 1865 | struct backing_dev_info *bdi = inode_to_bdi(inode); |
| 1866 | struct bdi_writeback *wb = NULL; |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1867 | int ratelimit; |
| 1868 | int *p; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1869 | |
Wu Fengguang | 36715ce | 2011-06-11 17:53:57 -0600 | [diff] [blame] | 1870 | if (!bdi_cap_account_dirty(bdi)) |
| 1871 | return; |
| 1872 | |
Tejun Heo | dfb8ae5 | 2015-05-22 17:13:40 -0400 | [diff] [blame] | 1873 | if (inode_cgwb_enabled(inode)) |
| 1874 | wb = wb_get_create_current(bdi, GFP_KERNEL); |
| 1875 | if (!wb) |
| 1876 | wb = &bdi->wb; |
| 1877 | |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1878 | ratelimit = current->nr_dirtied_pause; |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1879 | if (wb->dirty_exceeded) |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1880 | ratelimit = min(ratelimit, 32 >> (PAGE_SHIFT - 10)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1881 | |
Andrew Morton | fa5a734 | 2006-03-24 03:18:10 -0800 | [diff] [blame] | 1882 | preempt_disable(); |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1883 | /* |
| 1884 | * This prevents one CPU to accumulate too many dirtied pages without |
| 1885 | * calling into balance_dirty_pages(), which can happen when there are |
| 1886 | * 1000+ tasks, all of them start dirtying pages at exactly the same |
| 1887 | * time, hence all honoured too large initial task->nr_dirtied_pause. |
| 1888 | */ |
Christoph Lameter | 7c8e018 | 2014-06-04 16:07:56 -0700 | [diff] [blame] | 1889 | p = this_cpu_ptr(&bdp_ratelimits); |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1890 | if (unlikely(current->nr_dirtied >= ratelimit)) |
Andrew Morton | fa5a734 | 2006-03-24 03:18:10 -0800 | [diff] [blame] | 1891 | *p = 0; |
Wu Fengguang | d3bc1fe | 2011-04-14 07:52:37 -0600 | [diff] [blame] | 1892 | else if (unlikely(*p >= ratelimit_pages)) { |
| 1893 | *p = 0; |
| 1894 | ratelimit = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1895 | } |
Wu Fengguang | 54848d7 | 2011-04-05 13:21:19 -0600 | [diff] [blame] | 1896 | /* |
| 1897 | * Pick up the dirtied pages by the exited tasks. This avoids lots of |
| 1898 | * short-lived tasks (eg. gcc invocations in a kernel build) escaping |
| 1899 | * the dirty throttling and livelock other long-run dirtiers. |
| 1900 | */ |
Christoph Lameter | 7c8e018 | 2014-06-04 16:07:56 -0700 | [diff] [blame] | 1901 | p = this_cpu_ptr(&dirty_throttle_leaks); |
Wu Fengguang | 54848d7 | 2011-04-05 13:21:19 -0600 | [diff] [blame] | 1902 | if (*p > 0 && current->nr_dirtied < ratelimit) { |
Namjae Jeon | d0e1d66 | 2012-12-11 16:00:21 -0800 | [diff] [blame] | 1903 | unsigned long nr_pages_dirtied; |
Wu Fengguang | 54848d7 | 2011-04-05 13:21:19 -0600 | [diff] [blame] | 1904 | nr_pages_dirtied = min(*p, ratelimit - current->nr_dirtied); |
| 1905 | *p -= nr_pages_dirtied; |
| 1906 | current->nr_dirtied += nr_pages_dirtied; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1907 | } |
Andrew Morton | fa5a734 | 2006-03-24 03:18:10 -0800 | [diff] [blame] | 1908 | preempt_enable(); |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1909 | |
| 1910 | if (unlikely(current->nr_dirtied >= ratelimit)) |
Tahsin Erdogan | 4c578dc | 2017-11-15 17:33:19 -0800 | [diff] [blame] | 1911 | balance_dirty_pages(wb, current->nr_dirtied); |
Tejun Heo | dfb8ae5 | 2015-05-22 17:13:40 -0400 | [diff] [blame] | 1912 | |
| 1913 | wb_put(wb); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1914 | } |
Namjae Jeon | d0e1d66 | 2012-12-11 16:00:21 -0800 | [diff] [blame] | 1915 | EXPORT_SYMBOL(balance_dirty_pages_ratelimited); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1916 | |
Tejun Heo | aa661bb | 2015-05-22 18:23:31 -0400 | [diff] [blame] | 1917 | /** |
| 1918 | * wb_over_bg_thresh - does @wb need to be written back? |
| 1919 | * @wb: bdi_writeback of interest |
| 1920 | * |
| 1921 | * Determines whether background writeback should keep writing @wb or it's |
| 1922 | * clean enough. Returns %true if writeback should continue. |
| 1923 | */ |
| 1924 | bool wb_over_bg_thresh(struct bdi_writeback *wb) |
| 1925 | { |
Tejun Heo | 947e976 | 2015-05-22 18:23:32 -0400 | [diff] [blame] | 1926 | struct dirty_throttle_control gdtc_stor = { GDTC_INIT(wb) }; |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1927 | struct dirty_throttle_control mdtc_stor = { MDTC_INIT(wb, &gdtc_stor) }; |
Tejun Heo | 947e976 | 2015-05-22 18:23:32 -0400 | [diff] [blame] | 1928 | struct dirty_throttle_control * const gdtc = &gdtc_stor; |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1929 | struct dirty_throttle_control * const mdtc = mdtc_valid(&mdtc_stor) ? |
| 1930 | &mdtc_stor : NULL; |
Tejun Heo | aa661bb | 2015-05-22 18:23:31 -0400 | [diff] [blame] | 1931 | |
Tejun Heo | 947e976 | 2015-05-22 18:23:32 -0400 | [diff] [blame] | 1932 | /* |
| 1933 | * Similar to balance_dirty_pages() but ignores pages being written |
| 1934 | * as we're trying to decide whether to put more under writeback. |
| 1935 | */ |
| 1936 | gdtc->avail = global_dirtyable_memory(); |
Mel Gorman | 11fb998 | 2016-07-28 15:46:20 -0700 | [diff] [blame] | 1937 | gdtc->dirty = global_node_page_state(NR_FILE_DIRTY) + |
| 1938 | global_node_page_state(NR_UNSTABLE_NFS); |
Tejun Heo | 947e976 | 2015-05-22 18:23:32 -0400 | [diff] [blame] | 1939 | domain_dirty_limits(gdtc); |
Tejun Heo | aa661bb | 2015-05-22 18:23:31 -0400 | [diff] [blame] | 1940 | |
Tejun Heo | 947e976 | 2015-05-22 18:23:32 -0400 | [diff] [blame] | 1941 | if (gdtc->dirty > gdtc->bg_thresh) |
Tejun Heo | aa661bb | 2015-05-22 18:23:31 -0400 | [diff] [blame] | 1942 | return true; |
| 1943 | |
Howard Cochran | 74d3694 | 2016-03-10 01:12:39 -0500 | [diff] [blame] | 1944 | if (wb_stat(wb, WB_RECLAIMABLE) > |
| 1945 | wb_calc_thresh(gdtc->wb, gdtc->bg_thresh)) |
Tejun Heo | aa661bb | 2015-05-22 18:23:31 -0400 | [diff] [blame] | 1946 | return true; |
| 1947 | |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1948 | if (mdtc) { |
Tejun Heo | c5edf9c | 2015-09-29 13:04:26 -0400 | [diff] [blame] | 1949 | unsigned long filepages, headroom, writeback; |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1950 | |
Tejun Heo | c5edf9c | 2015-09-29 13:04:26 -0400 | [diff] [blame] | 1951 | mem_cgroup_wb_stats(wb, &filepages, &headroom, &mdtc->dirty, |
| 1952 | &writeback); |
| 1953 | mdtc_calc_avail(mdtc, filepages, headroom); |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1954 | domain_dirty_limits(mdtc); /* ditto, ignore writeback */ |
| 1955 | |
| 1956 | if (mdtc->dirty > mdtc->bg_thresh) |
| 1957 | return true; |
| 1958 | |
Howard Cochran | 74d3694 | 2016-03-10 01:12:39 -0500 | [diff] [blame] | 1959 | if (wb_stat(wb, WB_RECLAIMABLE) > |
| 1960 | wb_calc_thresh(mdtc->wb, mdtc->bg_thresh)) |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1961 | return true; |
| 1962 | } |
| 1963 | |
Tejun Heo | aa661bb | 2015-05-22 18:23:31 -0400 | [diff] [blame] | 1964 | return false; |
| 1965 | } |
| 1966 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1967 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1968 | * sysctl handler for /proc/sys/vm/dirty_writeback_centisecs |
| 1969 | */ |
Joe Perches | cccad5b | 2014-06-06 14:38:09 -0700 | [diff] [blame] | 1970 | int dirty_writeback_centisecs_handler(struct ctl_table *table, int write, |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 1971 | void __user *buffer, size_t *length, loff_t *ppos) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1972 | { |
Yafang Shao | 94af584 | 2017-10-10 05:44:13 +0800 | [diff] [blame] | 1973 | unsigned int old_interval = dirty_writeback_interval; |
| 1974 | int ret; |
| 1975 | |
| 1976 | ret = proc_dointvec(table, write, buffer, length, ppos); |
Yafang Shao | 515c24c | 2017-10-14 16:38:27 +0800 | [diff] [blame] | 1977 | |
| 1978 | /* |
| 1979 | * Writing 0 to dirty_writeback_interval will disable periodic writeback |
| 1980 | * and a different non-zero value will wakeup the writeback threads. |
| 1981 | * wb_wakeup_delayed() would be more appropriate, but it's a pain to |
| 1982 | * iterate over all bdis and wbs. |
| 1983 | * The reason we do this is to make the change take effect immediately. |
| 1984 | */ |
| 1985 | if (!ret && write && dirty_writeback_interval && |
| 1986 | dirty_writeback_interval != old_interval) |
Yafang Shao | 94af584 | 2017-10-10 05:44:13 +0800 | [diff] [blame] | 1987 | wakeup_flusher_threads(WB_REASON_PERIODIC); |
| 1988 | |
| 1989 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1990 | } |
| 1991 | |
Jens Axboe | c2c4986 | 2010-05-20 09:18:47 +0200 | [diff] [blame] | 1992 | #ifdef CONFIG_BLOCK |
Kees Cook | bca237a | 2017-08-28 15:03:41 -0700 | [diff] [blame] | 1993 | void laptop_mode_timer_fn(struct timer_list *t) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1994 | { |
Kees Cook | bca237a | 2017-08-28 15:03:41 -0700 | [diff] [blame] | 1995 | struct backing_dev_info *backing_dev_info = |
| 1996 | from_timer(backing_dev_info, t, laptop_mode_wb_timer); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1997 | |
Kees Cook | bca237a | 2017-08-28 15:03:41 -0700 | [diff] [blame] | 1998 | wakeup_flusher_threads_bdi(backing_dev_info, WB_REASON_LAPTOP_TIMER); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1999 | } |
| 2000 | |
| 2001 | /* |
| 2002 | * We've spun up the disk and we're in laptop mode: schedule writeback |
| 2003 | * of all dirty data a few seconds from now. If the flush is already scheduled |
| 2004 | * then push it back - the user is still using the disk. |
| 2005 | */ |
Matthew Garrett | 31373d0 | 2010-04-06 14:25:14 +0200 | [diff] [blame] | 2006 | void laptop_io_completion(struct backing_dev_info *info) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2007 | { |
Matthew Garrett | 31373d0 | 2010-04-06 14:25:14 +0200 | [diff] [blame] | 2008 | mod_timer(&info->laptop_mode_wb_timer, jiffies + laptop_mode); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2009 | } |
| 2010 | |
| 2011 | /* |
| 2012 | * We're in laptop mode and we've just synced. The sync's writes will have |
| 2013 | * caused another writeback to be scheduled by laptop_io_completion. |
| 2014 | * Nothing needs to be written back anymore, so we unschedule the writeback. |
| 2015 | */ |
| 2016 | void laptop_sync_completion(void) |
| 2017 | { |
Matthew Garrett | 31373d0 | 2010-04-06 14:25:14 +0200 | [diff] [blame] | 2018 | struct backing_dev_info *bdi; |
| 2019 | |
| 2020 | rcu_read_lock(); |
| 2021 | |
| 2022 | list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) |
| 2023 | del_timer(&bdi->laptop_mode_wb_timer); |
| 2024 | |
| 2025 | rcu_read_unlock(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2026 | } |
Jens Axboe | c2c4986 | 2010-05-20 09:18:47 +0200 | [diff] [blame] | 2027 | #endif |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2028 | |
| 2029 | /* |
| 2030 | * If ratelimit_pages is too high then we can get into dirty-data overload |
| 2031 | * if a large number of processes all perform writes at the same time. |
| 2032 | * If it is too low then SMP machines will call the (expensive) |
| 2033 | * get_writeback_state too often. |
| 2034 | * |
| 2035 | * Here we set ratelimit_pages to a level which ensures that when all CPUs are |
| 2036 | * dirtying in parallel, we cannot go more than 3% (1/32) over the dirty memory |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 2037 | * thresholds. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2038 | */ |
| 2039 | |
Chandra Seetharaman | 2d1d43f | 2006-09-29 02:01:25 -0700 | [diff] [blame] | 2040 | void writeback_set_ratelimit(void) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2041 | { |
Tejun Heo | dcc25ae | 2015-05-22 18:23:22 -0400 | [diff] [blame] | 2042 | struct wb_domain *dom = &global_wb_domain; |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 2043 | unsigned long background_thresh; |
| 2044 | unsigned long dirty_thresh; |
Tejun Heo | dcc25ae | 2015-05-22 18:23:22 -0400 | [diff] [blame] | 2045 | |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 2046 | global_dirty_limits(&background_thresh, &dirty_thresh); |
Tejun Heo | dcc25ae | 2015-05-22 18:23:22 -0400 | [diff] [blame] | 2047 | dom->dirty_limit = dirty_thresh; |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 2048 | ratelimit_pages = dirty_thresh / (num_online_cpus() * 32); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2049 | if (ratelimit_pages < 16) |
| 2050 | ratelimit_pages = 16; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2051 | } |
| 2052 | |
Sebastian Andrzej Siewior | 1d7ac6a | 2016-08-18 14:57:20 +0200 | [diff] [blame] | 2053 | static int page_writeback_cpu_online(unsigned int cpu) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2054 | { |
Sebastian Andrzej Siewior | 1d7ac6a | 2016-08-18 14:57:20 +0200 | [diff] [blame] | 2055 | writeback_set_ratelimit(); |
| 2056 | return 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2057 | } |
| 2058 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2059 | /* |
Linus Torvalds | dc6e29d | 2007-01-29 16:37:38 -0800 | [diff] [blame] | 2060 | * Called early on to tune the page writeback dirty limits. |
| 2061 | * |
| 2062 | * We used to scale dirty pages according to how total memory |
| 2063 | * related to pages that could be allocated for buffers (by |
| 2064 | * comparing nr_free_buffer_pages() to vm_total_pages. |
| 2065 | * |
| 2066 | * However, that was when we used "dirty_ratio" to scale with |
| 2067 | * all memory, and we don't do that any more. "dirty_ratio" |
| 2068 | * is now applied to total non-HIGHPAGE memory (by subtracting |
| 2069 | * totalhigh_pages from vm_total_pages), and as such we can't |
| 2070 | * get into the old insane situation any more where we had |
| 2071 | * large amounts of dirty pages compared to a small amount of |
| 2072 | * non-HIGHMEM memory. |
| 2073 | * |
| 2074 | * But we might still want to scale the dirty_ratio by how |
| 2075 | * much memory the box has.. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2076 | */ |
| 2077 | void __init page_writeback_init(void) |
| 2078 | { |
Rabin Vincent | a50fcb5 | 2015-08-06 15:47:14 -0700 | [diff] [blame] | 2079 | BUG_ON(wb_domain_init(&global_wb_domain, GFP_KERNEL)); |
| 2080 | |
Sebastian Andrzej Siewior | 1d7ac6a | 2016-08-18 14:57:20 +0200 | [diff] [blame] | 2081 | cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "mm/writeback:online", |
| 2082 | page_writeback_cpu_online, NULL); |
| 2083 | cpuhp_setup_state(CPUHP_MM_WRITEBACK_DEAD, "mm/writeback:dead", NULL, |
| 2084 | page_writeback_cpu_online); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2085 | } |
| 2086 | |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2087 | /** |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 2088 | * tag_pages_for_writeback - tag pages to be written by write_cache_pages |
| 2089 | * @mapping: address space structure to write |
| 2090 | * @start: starting page index |
| 2091 | * @end: ending page index (inclusive) |
| 2092 | * |
| 2093 | * This function scans the page range from @start to @end (inclusive) and tags |
| 2094 | * all pages that have DIRTY tag set with a special TOWRITE tag. The idea is |
| 2095 | * that write_cache_pages (or whoever calls this function) will then use |
| 2096 | * TOWRITE tag to identify pages eligible for writeback. This mechanism is |
| 2097 | * used to avoid livelocking of writeback by a process steadily creating new |
| 2098 | * dirty pages in the file (thus it is important for this function to be quick |
| 2099 | * so that it can tag pages faster than a dirtying process can create them). |
| 2100 | */ |
| 2101 | /* |
Matthew Wilcox | b93b016 | 2018-04-10 16:36:56 -0700 | [diff] [blame] | 2102 | * We tag pages in batches of WRITEBACK_TAG_BATCH to reduce the i_pages lock |
| 2103 | * latency. |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 2104 | */ |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 2105 | void tag_pages_for_writeback(struct address_space *mapping, |
| 2106 | pgoff_t start, pgoff_t end) |
| 2107 | { |
Randy Dunlap | 3c111a0 | 2010-08-11 14:17:30 -0700 | [diff] [blame] | 2108 | #define WRITEBACK_TAG_BATCH 4096 |
Matthew Wilcox | 268f42d | 2016-12-14 15:08:55 -0800 | [diff] [blame] | 2109 | unsigned long tagged = 0; |
| 2110 | struct radix_tree_iter iter; |
| 2111 | void **slot; |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 2112 | |
Matthew Wilcox | b93b016 | 2018-04-10 16:36:56 -0700 | [diff] [blame] | 2113 | xa_lock_irq(&mapping->i_pages); |
| 2114 | radix_tree_for_each_tagged(slot, &mapping->i_pages, &iter, start, |
Matthew Wilcox | 268f42d | 2016-12-14 15:08:55 -0800 | [diff] [blame] | 2115 | PAGECACHE_TAG_DIRTY) { |
| 2116 | if (iter.index > end) |
| 2117 | break; |
Matthew Wilcox | b93b016 | 2018-04-10 16:36:56 -0700 | [diff] [blame] | 2118 | radix_tree_iter_tag_set(&mapping->i_pages, &iter, |
Matthew Wilcox | 268f42d | 2016-12-14 15:08:55 -0800 | [diff] [blame] | 2119 | PAGECACHE_TAG_TOWRITE); |
| 2120 | tagged++; |
| 2121 | if ((tagged % WRITEBACK_TAG_BATCH) != 0) |
| 2122 | continue; |
| 2123 | slot = radix_tree_iter_resume(slot, &iter); |
Matthew Wilcox | b93b016 | 2018-04-10 16:36:56 -0700 | [diff] [blame] | 2124 | xa_unlock_irq(&mapping->i_pages); |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 2125 | cond_resched(); |
Matthew Wilcox | b93b016 | 2018-04-10 16:36:56 -0700 | [diff] [blame] | 2126 | xa_lock_irq(&mapping->i_pages); |
Matthew Wilcox | 268f42d | 2016-12-14 15:08:55 -0800 | [diff] [blame] | 2127 | } |
Matthew Wilcox | b93b016 | 2018-04-10 16:36:56 -0700 | [diff] [blame] | 2128 | xa_unlock_irq(&mapping->i_pages); |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 2129 | } |
| 2130 | EXPORT_SYMBOL(tag_pages_for_writeback); |
| 2131 | |
| 2132 | /** |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 2133 | * write_cache_pages - walk the list of dirty pages of the given address space and write all of them. |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2134 | * @mapping: address space structure to write |
| 2135 | * @wbc: subtract the number of written pages from *@wbc->nr_to_write |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 2136 | * @writepage: function called for each page |
| 2137 | * @data: data passed to writepage function |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2138 | * |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 2139 | * If a page is already under I/O, write_cache_pages() skips it, even |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2140 | * if it's dirty. This is desirable behaviour for memory-cleaning writeback, |
| 2141 | * but it is INCORRECT for data-integrity system calls such as fsync(). fsync() |
| 2142 | * and msync() need to guarantee that all the data which was dirty at the time |
| 2143 | * the call was made get new I/O started against them. If wbc->sync_mode is |
| 2144 | * WB_SYNC_ALL then we were called for data integrity and we must wait for |
| 2145 | * existing IO to complete. |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 2146 | * |
| 2147 | * To avoid livelocks (when other process dirties new pages), we first tag |
| 2148 | * pages which should be written back with TOWRITE tag and only then start |
| 2149 | * writing them. For data-integrity sync we have to be careful so that we do |
| 2150 | * not miss some pages (e.g., because some other process has cleared TOWRITE |
| 2151 | * tag we set). The rule we follow is that TOWRITE tag can be cleared only |
| 2152 | * by the process clearing the DIRTY tag (and submitting the page for IO). |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2153 | */ |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 2154 | int write_cache_pages(struct address_space *mapping, |
| 2155 | struct writeback_control *wbc, writepage_t writepage, |
| 2156 | void *data) |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2157 | { |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2158 | int ret = 0; |
| 2159 | int done = 0; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2160 | struct pagevec pvec; |
| 2161 | int nr_pages; |
Nick Piggin | 31a1266 | 2009-01-06 14:39:04 -0800 | [diff] [blame] | 2162 | pgoff_t uninitialized_var(writeback_index); |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2163 | pgoff_t index; |
| 2164 | pgoff_t end; /* Inclusive */ |
Nick Piggin | bd19e01 | 2009-01-06 14:39:06 -0800 | [diff] [blame] | 2165 | pgoff_t done_index; |
Nick Piggin | 31a1266 | 2009-01-06 14:39:04 -0800 | [diff] [blame] | 2166 | int cycled; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2167 | int range_whole = 0; |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 2168 | int tag; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2169 | |
Mel Gorman | 8667982 | 2017-11-15 17:37:52 -0800 | [diff] [blame] | 2170 | pagevec_init(&pvec); |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2171 | if (wbc->range_cyclic) { |
Nick Piggin | 31a1266 | 2009-01-06 14:39:04 -0800 | [diff] [blame] | 2172 | writeback_index = mapping->writeback_index; /* prev offset */ |
| 2173 | index = writeback_index; |
| 2174 | if (index == 0) |
| 2175 | cycled = 1; |
| 2176 | else |
| 2177 | cycled = 0; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2178 | end = -1; |
| 2179 | } else { |
Kirill A. Shutemov | 09cbfea | 2016-04-01 15:29:47 +0300 | [diff] [blame] | 2180 | index = wbc->range_start >> PAGE_SHIFT; |
| 2181 | end = wbc->range_end >> PAGE_SHIFT; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2182 | if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) |
| 2183 | range_whole = 1; |
Nick Piggin | 31a1266 | 2009-01-06 14:39:04 -0800 | [diff] [blame] | 2184 | cycled = 1; /* ignore range_cyclic tests */ |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2185 | } |
Wu Fengguang | 6e6938b | 2010-06-06 10:38:15 -0600 | [diff] [blame] | 2186 | if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages) |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 2187 | tag = PAGECACHE_TAG_TOWRITE; |
| 2188 | else |
| 2189 | tag = PAGECACHE_TAG_DIRTY; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2190 | retry: |
Wu Fengguang | 6e6938b | 2010-06-06 10:38:15 -0600 | [diff] [blame] | 2191 | if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages) |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 2192 | tag_pages_for_writeback(mapping, index, end); |
Nick Piggin | bd19e01 | 2009-01-06 14:39:06 -0800 | [diff] [blame] | 2193 | done_index = index; |
Nick Piggin | 5a3d5c9 | 2009-01-06 14:39:09 -0800 | [diff] [blame] | 2194 | while (!done && (index <= end)) { |
| 2195 | int i; |
| 2196 | |
Jan Kara | 2b9775a | 2017-11-15 17:35:09 -0800 | [diff] [blame] | 2197 | nr_pages = pagevec_lookup_range_tag(&pvec, mapping, &index, end, |
Jan Kara | 67fd707 | 2017-11-15 17:35:19 -0800 | [diff] [blame] | 2198 | tag); |
Nick Piggin | 5a3d5c9 | 2009-01-06 14:39:09 -0800 | [diff] [blame] | 2199 | if (nr_pages == 0) |
| 2200 | break; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2201 | |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2202 | for (i = 0; i < nr_pages; i++) { |
| 2203 | struct page *page = pvec.pages[i]; |
| 2204 | |
Jun'ichi Nomura | cf15b07 | 2011-03-22 16:33:40 -0700 | [diff] [blame] | 2205 | done_index = page->index; |
Nick Piggin | bd19e01 | 2009-01-06 14:39:06 -0800 | [diff] [blame] | 2206 | |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2207 | lock_page(page); |
| 2208 | |
Nick Piggin | 5a3d5c9 | 2009-01-06 14:39:09 -0800 | [diff] [blame] | 2209 | /* |
| 2210 | * Page truncated or invalidated. We can freely skip it |
| 2211 | * then, even for data integrity operations: the page |
| 2212 | * has disappeared concurrently, so there could be no |
| 2213 | * real expectation of this data interity operation |
| 2214 | * even if there is now a new, dirty page at the same |
| 2215 | * pagecache address. |
| 2216 | */ |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2217 | if (unlikely(page->mapping != mapping)) { |
Nick Piggin | 5a3d5c9 | 2009-01-06 14:39:09 -0800 | [diff] [blame] | 2218 | continue_unlock: |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2219 | unlock_page(page); |
| 2220 | continue; |
| 2221 | } |
| 2222 | |
Nick Piggin | 515f4a0 | 2009-01-06 14:39:10 -0800 | [diff] [blame] | 2223 | if (!PageDirty(page)) { |
| 2224 | /* someone wrote it for us */ |
| 2225 | goto continue_unlock; |
| 2226 | } |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2227 | |
Nick Piggin | 515f4a0 | 2009-01-06 14:39:10 -0800 | [diff] [blame] | 2228 | if (PageWriteback(page)) { |
| 2229 | if (wbc->sync_mode != WB_SYNC_NONE) |
| 2230 | wait_on_page_writeback(page); |
| 2231 | else |
| 2232 | goto continue_unlock; |
| 2233 | } |
| 2234 | |
| 2235 | BUG_ON(PageWriteback(page)); |
| 2236 | if (!clear_page_dirty_for_io(page)) |
Nick Piggin | 5a3d5c9 | 2009-01-06 14:39:09 -0800 | [diff] [blame] | 2237 | goto continue_unlock; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2238 | |
Christoph Hellwig | de1414a | 2015-01-14 10:42:36 +0100 | [diff] [blame] | 2239 | trace_wbc_writepage(wbc, inode_to_bdi(mapping->host)); |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 2240 | ret = (*writepage)(page, wbc, data); |
Nick Piggin | 0026677 | 2009-01-06 14:39:06 -0800 | [diff] [blame] | 2241 | if (unlikely(ret)) { |
| 2242 | if (ret == AOP_WRITEPAGE_ACTIVATE) { |
| 2243 | unlock_page(page); |
| 2244 | ret = 0; |
| 2245 | } else { |
| 2246 | /* |
| 2247 | * done_index is set past this page, |
| 2248 | * so media errors will not choke |
| 2249 | * background writeout for the entire |
| 2250 | * file. This has consequences for |
| 2251 | * range_cyclic semantics (ie. it may |
| 2252 | * not be suitable for data integrity |
| 2253 | * writeout). |
| 2254 | */ |
Jun'ichi Nomura | cf15b07 | 2011-03-22 16:33:40 -0700 | [diff] [blame] | 2255 | done_index = page->index + 1; |
Nick Piggin | 0026677 | 2009-01-06 14:39:06 -0800 | [diff] [blame] | 2256 | done = 1; |
| 2257 | break; |
| 2258 | } |
Dave Chinner | 0b56492 | 2010-06-09 10:37:18 +1000 | [diff] [blame] | 2259 | } |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2260 | |
Dave Chinner | 546a192 | 2010-08-24 11:44:34 +1000 | [diff] [blame] | 2261 | /* |
| 2262 | * We stop writing back only if we are not doing |
| 2263 | * integrity sync. In case of integrity sync we have to |
| 2264 | * keep going until we have written all the pages |
| 2265 | * we tagged for writeback prior to entering this loop. |
| 2266 | */ |
| 2267 | if (--wbc->nr_to_write <= 0 && |
| 2268 | wbc->sync_mode == WB_SYNC_NONE) { |
| 2269 | done = 1; |
| 2270 | break; |
Nick Piggin | 05fe478 | 2009-01-06 14:39:08 -0800 | [diff] [blame] | 2271 | } |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2272 | } |
| 2273 | pagevec_release(&pvec); |
| 2274 | cond_resched(); |
| 2275 | } |
Nick Piggin | 3a4c680 | 2009-02-12 04:34:23 +0100 | [diff] [blame] | 2276 | if (!cycled && !done) { |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2277 | /* |
Nick Piggin | 31a1266 | 2009-01-06 14:39:04 -0800 | [diff] [blame] | 2278 | * range_cyclic: |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2279 | * We hit the last page and there is more work to be done: wrap |
| 2280 | * back to the start of the file |
| 2281 | */ |
Nick Piggin | 31a1266 | 2009-01-06 14:39:04 -0800 | [diff] [blame] | 2282 | cycled = 1; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2283 | index = 0; |
Nick Piggin | 31a1266 | 2009-01-06 14:39:04 -0800 | [diff] [blame] | 2284 | end = writeback_index - 1; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2285 | goto retry; |
| 2286 | } |
Dave Chinner | 0b56492 | 2010-06-09 10:37:18 +1000 | [diff] [blame] | 2287 | if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0)) |
| 2288 | mapping->writeback_index = done_index; |
Aneesh Kumar K.V | 06d6cf6 | 2008-07-11 19:27:31 -0400 | [diff] [blame] | 2289 | |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2290 | return ret; |
| 2291 | } |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 2292 | EXPORT_SYMBOL(write_cache_pages); |
| 2293 | |
| 2294 | /* |
| 2295 | * Function used by generic_writepages to call the real writepage |
| 2296 | * function and set the mapping flags on error |
| 2297 | */ |
| 2298 | static int __writepage(struct page *page, struct writeback_control *wbc, |
| 2299 | void *data) |
| 2300 | { |
| 2301 | struct address_space *mapping = data; |
| 2302 | int ret = mapping->a_ops->writepage(page, wbc); |
| 2303 | mapping_set_error(mapping, ret); |
| 2304 | return ret; |
| 2305 | } |
| 2306 | |
| 2307 | /** |
| 2308 | * generic_writepages - walk the list of dirty pages of the given address space and writepage() all of them. |
| 2309 | * @mapping: address space structure to write |
| 2310 | * @wbc: subtract the number of written pages from *@wbc->nr_to_write |
| 2311 | * |
| 2312 | * This is a library function, which implements the writepages() |
| 2313 | * address_space_operation. |
| 2314 | */ |
| 2315 | int generic_writepages(struct address_space *mapping, |
| 2316 | struct writeback_control *wbc) |
| 2317 | { |
Shaohua Li | 9b6096a | 2011-03-17 10:47:06 +0100 | [diff] [blame] | 2318 | struct blk_plug plug; |
| 2319 | int ret; |
| 2320 | |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 2321 | /* deal with chardevs and other special file */ |
| 2322 | if (!mapping->a_ops->writepage) |
| 2323 | return 0; |
| 2324 | |
Shaohua Li | 9b6096a | 2011-03-17 10:47:06 +0100 | [diff] [blame] | 2325 | blk_start_plug(&plug); |
| 2326 | ret = write_cache_pages(mapping, wbc, __writepage, mapping); |
| 2327 | blk_finish_plug(&plug); |
| 2328 | return ret; |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 2329 | } |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2330 | |
| 2331 | EXPORT_SYMBOL(generic_writepages); |
| 2332 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2333 | int do_writepages(struct address_space *mapping, struct writeback_control *wbc) |
| 2334 | { |
Andrew Morton | 22905f7 | 2005-11-16 15:07:01 -0800 | [diff] [blame] | 2335 | int ret; |
| 2336 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2337 | if (wbc->nr_to_write <= 0) |
| 2338 | return 0; |
Theodore Ts'o | 80a2ea9 | 2017-04-28 09:51:54 -0400 | [diff] [blame] | 2339 | while (1) { |
| 2340 | if (mapping->a_ops->writepages) |
| 2341 | ret = mapping->a_ops->writepages(mapping, wbc); |
| 2342 | else |
| 2343 | ret = generic_writepages(mapping, wbc); |
| 2344 | if ((ret != -ENOMEM) || (wbc->sync_mode != WB_SYNC_ALL)) |
| 2345 | break; |
| 2346 | cond_resched(); |
| 2347 | congestion_wait(BLK_RW_ASYNC, HZ/50); |
| 2348 | } |
Andrew Morton | 22905f7 | 2005-11-16 15:07:01 -0800 | [diff] [blame] | 2349 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2350 | } |
| 2351 | |
| 2352 | /** |
Jeff Layton | 2b69c82 | 2017-07-05 15:26:48 -0400 | [diff] [blame] | 2353 | * write_one_page - write out a single page and wait on I/O |
Martin Waitz | 67be2dd | 2005-05-01 08:59:26 -0700 | [diff] [blame] | 2354 | * @page: the page to write |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2355 | * |
| 2356 | * The page must be locked by the caller and will be unlocked upon return. |
| 2357 | * |
Jeff Layton | 37e51a7 | 2017-07-05 15:17:19 -0400 | [diff] [blame] | 2358 | * Note that the mapping's AS_EIO/AS_ENOSPC flags will be cleared when this |
| 2359 | * function returns. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2360 | */ |
Jeff Layton | 2b69c82 | 2017-07-05 15:26:48 -0400 | [diff] [blame] | 2361 | int write_one_page(struct page *page) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2362 | { |
| 2363 | struct address_space *mapping = page->mapping; |
| 2364 | int ret = 0; |
| 2365 | struct writeback_control wbc = { |
| 2366 | .sync_mode = WB_SYNC_ALL, |
| 2367 | .nr_to_write = 1, |
| 2368 | }; |
| 2369 | |
| 2370 | BUG_ON(!PageLocked(page)); |
| 2371 | |
Jeff Layton | 2b69c82 | 2017-07-05 15:26:48 -0400 | [diff] [blame] | 2372 | wait_on_page_writeback(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2373 | |
| 2374 | if (clear_page_dirty_for_io(page)) { |
Kirill A. Shutemov | 09cbfea | 2016-04-01 15:29:47 +0300 | [diff] [blame] | 2375 | get_page(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2376 | ret = mapping->a_ops->writepage(page, &wbc); |
Jeff Layton | 37e51a7 | 2017-07-05 15:17:19 -0400 | [diff] [blame] | 2377 | if (ret == 0) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2378 | wait_on_page_writeback(page); |
Kirill A. Shutemov | 09cbfea | 2016-04-01 15:29:47 +0300 | [diff] [blame] | 2379 | put_page(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2380 | } else { |
| 2381 | unlock_page(page); |
| 2382 | } |
Jeff Layton | 37e51a7 | 2017-07-05 15:17:19 -0400 | [diff] [blame] | 2383 | |
| 2384 | if (!ret) |
| 2385 | ret = filemap_check_errors(mapping); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2386 | return ret; |
| 2387 | } |
| 2388 | EXPORT_SYMBOL(write_one_page); |
| 2389 | |
| 2390 | /* |
Ken Chen | 7671932 | 2007-02-10 01:43:15 -0800 | [diff] [blame] | 2391 | * For address_spaces which do not use buffers nor write back. |
| 2392 | */ |
| 2393 | int __set_page_dirty_no_writeback(struct page *page) |
| 2394 | { |
| 2395 | if (!PageDirty(page)) |
Bob Liu | c3f0da6 | 2011-01-13 15:45:49 -0800 | [diff] [blame] | 2396 | return !TestSetPageDirty(page); |
Ken Chen | 7671932 | 2007-02-10 01:43:15 -0800 | [diff] [blame] | 2397 | return 0; |
| 2398 | } |
| 2399 | |
| 2400 | /* |
Edward Shishkin | e3a7cca | 2009-03-31 15:19:39 -0700 | [diff] [blame] | 2401 | * Helper function for set_page_dirty family. |
Greg Thelen | c4843a7 | 2015-05-22 17:13:16 -0400 | [diff] [blame] | 2402 | * |
Johannes Weiner | 81f8c3a | 2016-03-15 14:57:04 -0700 | [diff] [blame] | 2403 | * Caller must hold lock_page_memcg(). |
Greg Thelen | c4843a7 | 2015-05-22 17:13:16 -0400 | [diff] [blame] | 2404 | * |
Edward Shishkin | e3a7cca | 2009-03-31 15:19:39 -0700 | [diff] [blame] | 2405 | * NOTE: This relies on being atomic wrt interrupts. |
| 2406 | */ |
Johannes Weiner | 62cccb8 | 2016-03-15 14:57:22 -0700 | [diff] [blame] | 2407 | void account_page_dirtied(struct page *page, struct address_space *mapping) |
Edward Shishkin | e3a7cca | 2009-03-31 15:19:39 -0700 | [diff] [blame] | 2408 | { |
Tejun Heo | 52ebea7 | 2015-05-22 17:13:37 -0400 | [diff] [blame] | 2409 | struct inode *inode = mapping->host; |
| 2410 | |
Tejun Heo | 9fb0a7d | 2013-01-11 13:06:37 -0800 | [diff] [blame] | 2411 | trace_writeback_dirty_page(page, mapping); |
| 2412 | |
Edward Shishkin | e3a7cca | 2009-03-31 15:19:39 -0700 | [diff] [blame] | 2413 | if (mapping_cap_account_dirty(mapping)) { |
Tejun Heo | 52ebea7 | 2015-05-22 17:13:37 -0400 | [diff] [blame] | 2414 | struct bdi_writeback *wb; |
Christoph Hellwig | de1414a | 2015-01-14 10:42:36 +0100 | [diff] [blame] | 2415 | |
Tejun Heo | 52ebea7 | 2015-05-22 17:13:37 -0400 | [diff] [blame] | 2416 | inode_attach_wb(inode, page); |
| 2417 | wb = inode_to_wb(inode); |
Edward Shishkin | e3a7cca | 2009-03-31 15:19:39 -0700 | [diff] [blame] | 2418 | |
Johannes Weiner | 00f3ca2 | 2017-07-06 15:40:52 -0700 | [diff] [blame] | 2419 | __inc_lruvec_page_state(page, NR_FILE_DIRTY); |
Mel Gorman | 5a1c84b | 2016-07-28 15:47:31 -0700 | [diff] [blame] | 2420 | __inc_zone_page_state(page, NR_ZONE_WRITE_PENDING); |
Mel Gorman | c4a2563 | 2016-07-28 15:46:23 -0700 | [diff] [blame] | 2421 | __inc_node_page_state(page, NR_DIRTIED); |
Nikolay Borisov | 3e8f399 | 2017-07-12 14:37:51 -0700 | [diff] [blame] | 2422 | inc_wb_stat(wb, WB_RECLAIMABLE); |
| 2423 | inc_wb_stat(wb, WB_DIRTIED); |
Kirill A. Shutemov | 09cbfea | 2016-04-01 15:29:47 +0300 | [diff] [blame] | 2424 | task_io_account_write(PAGE_SIZE); |
Wu Fengguang | d3bc1fe | 2011-04-14 07:52:37 -0600 | [diff] [blame] | 2425 | current->nr_dirtied++; |
| 2426 | this_cpu_inc(bdp_ratelimits); |
Edward Shishkin | e3a7cca | 2009-03-31 15:19:39 -0700 | [diff] [blame] | 2427 | } |
| 2428 | } |
Michael Rubin | 679ceac | 2010-08-20 02:31:26 -0700 | [diff] [blame] | 2429 | EXPORT_SYMBOL(account_page_dirtied); |
Edward Shishkin | e3a7cca | 2009-03-31 15:19:39 -0700 | [diff] [blame] | 2430 | |
| 2431 | /* |
Konstantin Khlebnikov | b9ea251 | 2015-04-14 15:45:27 -0700 | [diff] [blame] | 2432 | * Helper function for deaccounting dirty page without writeback. |
| 2433 | * |
Johannes Weiner | 81f8c3a | 2016-03-15 14:57:04 -0700 | [diff] [blame] | 2434 | * Caller must hold lock_page_memcg(). |
Konstantin Khlebnikov | b9ea251 | 2015-04-14 15:45:27 -0700 | [diff] [blame] | 2435 | */ |
Greg Thelen | c4843a7 | 2015-05-22 17:13:16 -0400 | [diff] [blame] | 2436 | void account_page_cleaned(struct page *page, struct address_space *mapping, |
Johannes Weiner | 62cccb8 | 2016-03-15 14:57:22 -0700 | [diff] [blame] | 2437 | struct bdi_writeback *wb) |
Konstantin Khlebnikov | b9ea251 | 2015-04-14 15:45:27 -0700 | [diff] [blame] | 2438 | { |
| 2439 | if (mapping_cap_account_dirty(mapping)) { |
Johannes Weiner | 00f3ca2 | 2017-07-06 15:40:52 -0700 | [diff] [blame] | 2440 | dec_lruvec_page_state(page, NR_FILE_DIRTY); |
Mel Gorman | 5a1c84b | 2016-07-28 15:47:31 -0700 | [diff] [blame] | 2441 | dec_zone_page_state(page, NR_ZONE_WRITE_PENDING); |
Tejun Heo | 682aa8e | 2015-05-28 14:50:53 -0400 | [diff] [blame] | 2442 | dec_wb_stat(wb, WB_RECLAIMABLE); |
Kirill A. Shutemov | 09cbfea | 2016-04-01 15:29:47 +0300 | [diff] [blame] | 2443 | task_io_account_cancelled_write(PAGE_SIZE); |
Konstantin Khlebnikov | b9ea251 | 2015-04-14 15:45:27 -0700 | [diff] [blame] | 2444 | } |
| 2445 | } |
Konstantin Khlebnikov | b9ea251 | 2015-04-14 15:45:27 -0700 | [diff] [blame] | 2446 | |
| 2447 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2448 | * For address_spaces which do not use buffers. Just tag the page as dirty in |
| 2449 | * its radix tree. |
| 2450 | * |
| 2451 | * This is also used when a single buffer is being dirtied: we want to set the |
| 2452 | * page dirty in that case, but not all the buffers. This is a "bottom-up" |
| 2453 | * dirtying, whereas __set_page_dirty_buffers() is a "top-down" dirtying. |
| 2454 | * |
Johannes Weiner | 2d6d7f9 | 2015-01-08 14:32:18 -0800 | [diff] [blame] | 2455 | * The caller must ensure this doesn't race with truncation. Most will simply |
| 2456 | * hold the page lock, but e.g. zap_pte_range() calls with the page mapped and |
| 2457 | * the pte lock held, which also locks out truncation. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2458 | */ |
| 2459 | int __set_page_dirty_nobuffers(struct page *page) |
| 2460 | { |
Johannes Weiner | 62cccb8 | 2016-03-15 14:57:22 -0700 | [diff] [blame] | 2461 | lock_page_memcg(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2462 | if (!TestSetPageDirty(page)) { |
| 2463 | struct address_space *mapping = page_mapping(page); |
KOSAKI Motohiro | a85d9df | 2014-02-06 12:04:24 -0800 | [diff] [blame] | 2464 | unsigned long flags; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2465 | |
Greg Thelen | c4843a7 | 2015-05-22 17:13:16 -0400 | [diff] [blame] | 2466 | if (!mapping) { |
Johannes Weiner | 62cccb8 | 2016-03-15 14:57:22 -0700 | [diff] [blame] | 2467 | unlock_page_memcg(page); |
Andrew Morton | 8c08540 | 2006-12-10 02:19:24 -0800 | [diff] [blame] | 2468 | return 1; |
Greg Thelen | c4843a7 | 2015-05-22 17:13:16 -0400 | [diff] [blame] | 2469 | } |
Andrew Morton | 8c08540 | 2006-12-10 02:19:24 -0800 | [diff] [blame] | 2470 | |
Matthew Wilcox | b93b016 | 2018-04-10 16:36:56 -0700 | [diff] [blame] | 2471 | xa_lock_irqsave(&mapping->i_pages, flags); |
Johannes Weiner | 2d6d7f9 | 2015-01-08 14:32:18 -0800 | [diff] [blame] | 2472 | BUG_ON(page_mapping(page) != mapping); |
| 2473 | WARN_ON_ONCE(!PagePrivate(page) && !PageUptodate(page)); |
Johannes Weiner | 62cccb8 | 2016-03-15 14:57:22 -0700 | [diff] [blame] | 2474 | account_page_dirtied(page, mapping); |
Matthew Wilcox | b93b016 | 2018-04-10 16:36:56 -0700 | [diff] [blame] | 2475 | radix_tree_tag_set(&mapping->i_pages, page_index(page), |
Johannes Weiner | 2d6d7f9 | 2015-01-08 14:32:18 -0800 | [diff] [blame] | 2476 | PAGECACHE_TAG_DIRTY); |
Matthew Wilcox | b93b016 | 2018-04-10 16:36:56 -0700 | [diff] [blame] | 2477 | xa_unlock_irqrestore(&mapping->i_pages, flags); |
Johannes Weiner | 62cccb8 | 2016-03-15 14:57:22 -0700 | [diff] [blame] | 2478 | unlock_page_memcg(page); |
Greg Thelen | c4843a7 | 2015-05-22 17:13:16 -0400 | [diff] [blame] | 2479 | |
Andrew Morton | 8c08540 | 2006-12-10 02:19:24 -0800 | [diff] [blame] | 2480 | if (mapping->host) { |
| 2481 | /* !PageAnon && !swapper_space */ |
| 2482 | __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2483 | } |
Andrew Morton | 4741c9f | 2006-03-24 03:18:11 -0800 | [diff] [blame] | 2484 | return 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2485 | } |
Johannes Weiner | 62cccb8 | 2016-03-15 14:57:22 -0700 | [diff] [blame] | 2486 | unlock_page_memcg(page); |
Andrew Morton | 4741c9f | 2006-03-24 03:18:11 -0800 | [diff] [blame] | 2487 | return 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2488 | } |
| 2489 | EXPORT_SYMBOL(__set_page_dirty_nobuffers); |
| 2490 | |
| 2491 | /* |
Wu Fengguang | 2f800fb | 2011-08-08 15:22:00 -0600 | [diff] [blame] | 2492 | * Call this whenever redirtying a page, to de-account the dirty counters |
| 2493 | * (NR_DIRTIED, BDI_DIRTIED, tsk->nr_dirtied), so that they match the written |
| 2494 | * counters (NR_WRITTEN, BDI_WRITTEN) in long term. The mismatches will lead to |
| 2495 | * systematic errors in balanced_dirty_ratelimit and the dirty pages position |
| 2496 | * control. |
| 2497 | */ |
| 2498 | void account_page_redirty(struct page *page) |
| 2499 | { |
| 2500 | struct address_space *mapping = page->mapping; |
Tejun Heo | 9101813 | 2015-05-22 17:13:39 -0400 | [diff] [blame] | 2501 | |
Wu Fengguang | 2f800fb | 2011-08-08 15:22:00 -0600 | [diff] [blame] | 2502 | if (mapping && mapping_cap_account_dirty(mapping)) { |
Tejun Heo | 682aa8e | 2015-05-28 14:50:53 -0400 | [diff] [blame] | 2503 | struct inode *inode = mapping->host; |
| 2504 | struct bdi_writeback *wb; |
Greg Thelen | 2e898e4 | 2018-04-20 14:55:42 -0700 | [diff] [blame] | 2505 | struct wb_lock_cookie cookie = {}; |
Tejun Heo | 9101813 | 2015-05-22 17:13:39 -0400 | [diff] [blame] | 2506 | |
Greg Thelen | 2e898e4 | 2018-04-20 14:55:42 -0700 | [diff] [blame] | 2507 | wb = unlocked_inode_to_wb_begin(inode, &cookie); |
Wu Fengguang | 2f800fb | 2011-08-08 15:22:00 -0600 | [diff] [blame] | 2508 | current->nr_dirtied--; |
Mel Gorman | c4a2563 | 2016-07-28 15:46:23 -0700 | [diff] [blame] | 2509 | dec_node_page_state(page, NR_DIRTIED); |
Tejun Heo | 9101813 | 2015-05-22 17:13:39 -0400 | [diff] [blame] | 2510 | dec_wb_stat(wb, WB_DIRTIED); |
Greg Thelen | 2e898e4 | 2018-04-20 14:55:42 -0700 | [diff] [blame] | 2511 | unlocked_inode_to_wb_end(inode, &cookie); |
Wu Fengguang | 2f800fb | 2011-08-08 15:22:00 -0600 | [diff] [blame] | 2512 | } |
| 2513 | } |
| 2514 | EXPORT_SYMBOL(account_page_redirty); |
| 2515 | |
| 2516 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2517 | * When a writepage implementation decides that it doesn't want to write this |
| 2518 | * page for some reason, it should redirty the locked page via |
| 2519 | * redirty_page_for_writepage() and it should then unlock the page and return 0 |
| 2520 | */ |
| 2521 | int redirty_page_for_writepage(struct writeback_control *wbc, struct page *page) |
| 2522 | { |
Konstantin Khebnikov | 8d38633 | 2015-02-11 15:26:55 -0800 | [diff] [blame] | 2523 | int ret; |
| 2524 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2525 | wbc->pages_skipped++; |
Konstantin Khebnikov | 8d38633 | 2015-02-11 15:26:55 -0800 | [diff] [blame] | 2526 | ret = __set_page_dirty_nobuffers(page); |
Wu Fengguang | 2f800fb | 2011-08-08 15:22:00 -0600 | [diff] [blame] | 2527 | account_page_redirty(page); |
Konstantin Khebnikov | 8d38633 | 2015-02-11 15:26:55 -0800 | [diff] [blame] | 2528 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2529 | } |
| 2530 | EXPORT_SYMBOL(redirty_page_for_writepage); |
| 2531 | |
| 2532 | /* |
Wu Fengguang | 6746aff | 2009-09-16 11:50:14 +0200 | [diff] [blame] | 2533 | * Dirty a page. |
| 2534 | * |
| 2535 | * For pages with a mapping this should be done under the page lock |
| 2536 | * for the benefit of asynchronous memory errors who prefer a consistent |
| 2537 | * dirty state. This rule can be broken in some special cases, |
| 2538 | * but should be better not to. |
| 2539 | * |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2540 | * If the mapping doesn't provide a set_page_dirty a_op, then |
| 2541 | * just fall through and assume that it wants buffer_heads. |
| 2542 | */ |
Nick Piggin | 1cf6e7d | 2009-02-18 14:48:18 -0800 | [diff] [blame] | 2543 | int set_page_dirty(struct page *page) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2544 | { |
| 2545 | struct address_space *mapping = page_mapping(page); |
| 2546 | |
Kirill A. Shutemov | 800d8c6 | 2016-07-26 15:26:18 -0700 | [diff] [blame] | 2547 | page = compound_head(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2548 | if (likely(mapping)) { |
| 2549 | int (*spd)(struct page *) = mapping->a_ops->set_page_dirty; |
Minchan Kim | 278df9f | 2011-03-22 16:32:54 -0700 | [diff] [blame] | 2550 | /* |
| 2551 | * readahead/lru_deactivate_page could remain |
| 2552 | * PG_readahead/PG_reclaim due to race with end_page_writeback |
| 2553 | * About readahead, if the page is written, the flags would be |
| 2554 | * reset. So no problem. |
| 2555 | * About lru_deactivate_page, if the page is redirty, the flag |
| 2556 | * will be reset. So no problem. but if the page is used by readahead |
| 2557 | * it will confuse readahead and make it restart the size rampup |
| 2558 | * process. But it's a trivial problem. |
| 2559 | */ |
Naoya Horiguchi | a4bb3ec | 2015-04-15 16:13:17 -0700 | [diff] [blame] | 2560 | if (PageReclaim(page)) |
| 2561 | ClearPageReclaim(page); |
David Howells | 9361401 | 2006-09-30 20:45:40 +0200 | [diff] [blame] | 2562 | #ifdef CONFIG_BLOCK |
| 2563 | if (!spd) |
| 2564 | spd = __set_page_dirty_buffers; |
| 2565 | #endif |
| 2566 | return (*spd)(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2567 | } |
Andrew Morton | 4741c9f | 2006-03-24 03:18:11 -0800 | [diff] [blame] | 2568 | if (!PageDirty(page)) { |
| 2569 | if (!TestSetPageDirty(page)) |
| 2570 | return 1; |
| 2571 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2572 | return 0; |
| 2573 | } |
| 2574 | EXPORT_SYMBOL(set_page_dirty); |
| 2575 | |
| 2576 | /* |
| 2577 | * set_page_dirty() is racy if the caller has no reference against |
| 2578 | * page->mapping->host, and if the page is unlocked. This is because another |
| 2579 | * CPU could truncate the page off the mapping and then free the mapping. |
| 2580 | * |
| 2581 | * Usually, the page _is_ locked, or the caller is a user-space process which |
| 2582 | * holds a reference on the inode by having an open file. |
| 2583 | * |
| 2584 | * In other cases, the page should be locked before running set_page_dirty(). |
| 2585 | */ |
| 2586 | int set_page_dirty_lock(struct page *page) |
| 2587 | { |
| 2588 | int ret; |
| 2589 | |
Jens Axboe | 7eaceac | 2011-03-10 08:52:07 +0100 | [diff] [blame] | 2590 | lock_page(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2591 | ret = set_page_dirty(page); |
| 2592 | unlock_page(page); |
| 2593 | return ret; |
| 2594 | } |
| 2595 | EXPORT_SYMBOL(set_page_dirty_lock); |
| 2596 | |
| 2597 | /* |
Tejun Heo | 11f81be | 2015-05-22 17:13:15 -0400 | [diff] [blame] | 2598 | * This cancels just the dirty bit on the kernel page itself, it does NOT |
| 2599 | * actually remove dirty bits on any mmap's that may be around. It also |
| 2600 | * leaves the page tagged dirty, so any sync activity will still find it on |
| 2601 | * the dirty lists, and in particular, clear_page_dirty_for_io() will still |
| 2602 | * look at the dirty bits in the VM. |
| 2603 | * |
| 2604 | * Doing this should *normally* only ever be done when a page is truncated, |
| 2605 | * and is not actually mapped anywhere at all. However, fs/buffer.c does |
| 2606 | * this when it notices that somebody has cleaned out all the buffers on a |
| 2607 | * page without actually doing it through the VM. Can you say "ext3 is |
| 2608 | * horribly ugly"? Thought you could. |
| 2609 | */ |
Jan Kara | 736304f | 2017-11-15 17:37:11 -0800 | [diff] [blame] | 2610 | void __cancel_dirty_page(struct page *page) |
Tejun Heo | 11f81be | 2015-05-22 17:13:15 -0400 | [diff] [blame] | 2611 | { |
Greg Thelen | c4843a7 | 2015-05-22 17:13:16 -0400 | [diff] [blame] | 2612 | struct address_space *mapping = page_mapping(page); |
| 2613 | |
| 2614 | if (mapping_cap_account_dirty(mapping)) { |
Tejun Heo | 682aa8e | 2015-05-28 14:50:53 -0400 | [diff] [blame] | 2615 | struct inode *inode = mapping->host; |
| 2616 | struct bdi_writeback *wb; |
Greg Thelen | 2e898e4 | 2018-04-20 14:55:42 -0700 | [diff] [blame] | 2617 | struct wb_lock_cookie cookie = {}; |
Greg Thelen | c4843a7 | 2015-05-22 17:13:16 -0400 | [diff] [blame] | 2618 | |
Johannes Weiner | 62cccb8 | 2016-03-15 14:57:22 -0700 | [diff] [blame] | 2619 | lock_page_memcg(page); |
Greg Thelen | 2e898e4 | 2018-04-20 14:55:42 -0700 | [diff] [blame] | 2620 | wb = unlocked_inode_to_wb_begin(inode, &cookie); |
Greg Thelen | c4843a7 | 2015-05-22 17:13:16 -0400 | [diff] [blame] | 2621 | |
| 2622 | if (TestClearPageDirty(page)) |
Johannes Weiner | 62cccb8 | 2016-03-15 14:57:22 -0700 | [diff] [blame] | 2623 | account_page_cleaned(page, mapping, wb); |
Greg Thelen | c4843a7 | 2015-05-22 17:13:16 -0400 | [diff] [blame] | 2624 | |
Greg Thelen | 2e898e4 | 2018-04-20 14:55:42 -0700 | [diff] [blame] | 2625 | unlocked_inode_to_wb_end(inode, &cookie); |
Johannes Weiner | 62cccb8 | 2016-03-15 14:57:22 -0700 | [diff] [blame] | 2626 | unlock_page_memcg(page); |
Greg Thelen | c4843a7 | 2015-05-22 17:13:16 -0400 | [diff] [blame] | 2627 | } else { |
| 2628 | ClearPageDirty(page); |
| 2629 | } |
Tejun Heo | 11f81be | 2015-05-22 17:13:15 -0400 | [diff] [blame] | 2630 | } |
Jan Kara | 736304f | 2017-11-15 17:37:11 -0800 | [diff] [blame] | 2631 | EXPORT_SYMBOL(__cancel_dirty_page); |
Tejun Heo | 11f81be | 2015-05-22 17:13:15 -0400 | [diff] [blame] | 2632 | |
| 2633 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2634 | * Clear a page's dirty flag, while caring for dirty memory accounting. |
| 2635 | * Returns true if the page was previously dirty. |
| 2636 | * |
| 2637 | * This is for preparing to put the page under writeout. We leave the page |
| 2638 | * tagged as dirty in the radix tree so that a concurrent write-for-sync |
| 2639 | * can discover it via a PAGECACHE_TAG_DIRTY walk. The ->writepage |
| 2640 | * implementation will run either set_page_writeback() or set_page_dirty(), |
| 2641 | * at which stage we bring the page's dirty flag and radix-tree dirty tag |
| 2642 | * back into sync. |
| 2643 | * |
| 2644 | * This incoherency between the page's dirty flag and radix-tree tag is |
| 2645 | * unfortunate, but it only exists while the page is locked. |
| 2646 | */ |
| 2647 | int clear_page_dirty_for_io(struct page *page) |
| 2648 | { |
| 2649 | struct address_space *mapping = page_mapping(page); |
Greg Thelen | c4843a7 | 2015-05-22 17:13:16 -0400 | [diff] [blame] | 2650 | int ret = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2651 | |
Nick Piggin | 7935289 | 2007-07-19 01:47:22 -0700 | [diff] [blame] | 2652 | BUG_ON(!PageLocked(page)); |
| 2653 | |
Linus Torvalds | 7658cc2 | 2006-12-29 10:00:58 -0800 | [diff] [blame] | 2654 | if (mapping && mapping_cap_account_dirty(mapping)) { |
Tejun Heo | 682aa8e | 2015-05-28 14:50:53 -0400 | [diff] [blame] | 2655 | struct inode *inode = mapping->host; |
| 2656 | struct bdi_writeback *wb; |
Greg Thelen | 2e898e4 | 2018-04-20 14:55:42 -0700 | [diff] [blame] | 2657 | struct wb_lock_cookie cookie = {}; |
Tejun Heo | 682aa8e | 2015-05-28 14:50:53 -0400 | [diff] [blame] | 2658 | |
Linus Torvalds | 7658cc2 | 2006-12-29 10:00:58 -0800 | [diff] [blame] | 2659 | /* |
| 2660 | * Yes, Virginia, this is indeed insane. |
| 2661 | * |
| 2662 | * We use this sequence to make sure that |
| 2663 | * (a) we account for dirty stats properly |
| 2664 | * (b) we tell the low-level filesystem to |
| 2665 | * mark the whole page dirty if it was |
| 2666 | * dirty in a pagetable. Only to then |
| 2667 | * (c) clean the page again and return 1 to |
| 2668 | * cause the writeback. |
| 2669 | * |
| 2670 | * This way we avoid all nasty races with the |
| 2671 | * dirty bit in multiple places and clearing |
| 2672 | * them concurrently from different threads. |
| 2673 | * |
| 2674 | * Note! Normally the "set_page_dirty(page)" |
| 2675 | * has no effect on the actual dirty bit - since |
| 2676 | * that will already usually be set. But we |
| 2677 | * need the side effects, and it can help us |
| 2678 | * avoid races. |
| 2679 | * |
| 2680 | * We basically use the page "master dirty bit" |
| 2681 | * as a serialization point for all the different |
| 2682 | * threads doing their things. |
Linus Torvalds | 7658cc2 | 2006-12-29 10:00:58 -0800 | [diff] [blame] | 2683 | */ |
| 2684 | if (page_mkclean(page)) |
| 2685 | set_page_dirty(page); |
Nick Piggin | 7935289 | 2007-07-19 01:47:22 -0700 | [diff] [blame] | 2686 | /* |
| 2687 | * We carefully synchronise fault handlers against |
| 2688 | * installing a dirty pte and marking the page dirty |
Johannes Weiner | 2d6d7f9 | 2015-01-08 14:32:18 -0800 | [diff] [blame] | 2689 | * at this point. We do this by having them hold the |
| 2690 | * page lock while dirtying the page, and pages are |
| 2691 | * always locked coming in here, so we get the desired |
| 2692 | * exclusion. |
Nick Piggin | 7935289 | 2007-07-19 01:47:22 -0700 | [diff] [blame] | 2693 | */ |
Greg Thelen | 2e898e4 | 2018-04-20 14:55:42 -0700 | [diff] [blame] | 2694 | wb = unlocked_inode_to_wb_begin(inode, &cookie); |
Linus Torvalds | 7658cc2 | 2006-12-29 10:00:58 -0800 | [diff] [blame] | 2695 | if (TestClearPageDirty(page)) { |
Johannes Weiner | 00f3ca2 | 2017-07-06 15:40:52 -0700 | [diff] [blame] | 2696 | dec_lruvec_page_state(page, NR_FILE_DIRTY); |
Mel Gorman | 5a1c84b | 2016-07-28 15:47:31 -0700 | [diff] [blame] | 2697 | dec_zone_page_state(page, NR_ZONE_WRITE_PENDING); |
Tejun Heo | 682aa8e | 2015-05-28 14:50:53 -0400 | [diff] [blame] | 2698 | dec_wb_stat(wb, WB_RECLAIMABLE); |
Greg Thelen | c4843a7 | 2015-05-22 17:13:16 -0400 | [diff] [blame] | 2699 | ret = 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2700 | } |
Greg Thelen | 2e898e4 | 2018-04-20 14:55:42 -0700 | [diff] [blame] | 2701 | unlocked_inode_to_wb_end(inode, &cookie); |
Greg Thelen | c4843a7 | 2015-05-22 17:13:16 -0400 | [diff] [blame] | 2702 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2703 | } |
Linus Torvalds | 7658cc2 | 2006-12-29 10:00:58 -0800 | [diff] [blame] | 2704 | return TestClearPageDirty(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2705 | } |
Hans Reiser | 58bb01a | 2005-11-18 01:10:53 -0800 | [diff] [blame] | 2706 | EXPORT_SYMBOL(clear_page_dirty_for_io); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2707 | |
| 2708 | int test_clear_page_writeback(struct page *page) |
| 2709 | { |
| 2710 | struct address_space *mapping = page_mapping(page); |
Johannes Weiner | 739f79f | 2017-08-18 15:15:48 -0700 | [diff] [blame] | 2711 | struct mem_cgroup *memcg; |
| 2712 | struct lruvec *lruvec; |
Johannes Weiner | d7365e7 | 2014-10-29 14:50:48 -0700 | [diff] [blame] | 2713 | int ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2714 | |
Johannes Weiner | 739f79f | 2017-08-18 15:15:48 -0700 | [diff] [blame] | 2715 | memcg = lock_page_memcg(page); |
| 2716 | lruvec = mem_cgroup_page_lruvec(page, page_pgdat(page)); |
Huang Ying | 371a096 | 2016-10-07 16:59:30 -0700 | [diff] [blame] | 2717 | if (mapping && mapping_use_writeback_tags(mapping)) { |
Tejun Heo | 9101813 | 2015-05-22 17:13:39 -0400 | [diff] [blame] | 2718 | struct inode *inode = mapping->host; |
| 2719 | struct backing_dev_info *bdi = inode_to_bdi(inode); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2720 | unsigned long flags; |
| 2721 | |
Matthew Wilcox | b93b016 | 2018-04-10 16:36:56 -0700 | [diff] [blame] | 2722 | xa_lock_irqsave(&mapping->i_pages, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2723 | ret = TestClearPageWriteback(page); |
Peter Zijlstra | 69cb51d | 2007-10-16 23:25:48 -0700 | [diff] [blame] | 2724 | if (ret) { |
Matthew Wilcox | b93b016 | 2018-04-10 16:36:56 -0700 | [diff] [blame] | 2725 | radix_tree_tag_clear(&mapping->i_pages, page_index(page), |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2726 | PAGECACHE_TAG_WRITEBACK); |
Miklos Szeredi | e4ad08f | 2008-04-30 00:54:37 -0700 | [diff] [blame] | 2727 | if (bdi_cap_account_writeback(bdi)) { |
Tejun Heo | 9101813 | 2015-05-22 17:13:39 -0400 | [diff] [blame] | 2728 | struct bdi_writeback *wb = inode_to_wb(inode); |
| 2729 | |
Nikolay Borisov | 3e8f399 | 2017-07-12 14:37:51 -0700 | [diff] [blame] | 2730 | dec_wb_stat(wb, WB_WRITEBACK); |
Tejun Heo | 9101813 | 2015-05-22 17:13:39 -0400 | [diff] [blame] | 2731 | __wb_writeout_inc(wb); |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 2732 | } |
Peter Zijlstra | 69cb51d | 2007-10-16 23:25:48 -0700 | [diff] [blame] | 2733 | } |
Dave Chinner | 6c60d2b | 2016-07-26 15:21:50 -0700 | [diff] [blame] | 2734 | |
| 2735 | if (mapping->host && !mapping_tagged(mapping, |
| 2736 | PAGECACHE_TAG_WRITEBACK)) |
| 2737 | sb_clear_inode_writeback(mapping->host); |
| 2738 | |
Matthew Wilcox | b93b016 | 2018-04-10 16:36:56 -0700 | [diff] [blame] | 2739 | xa_unlock_irqrestore(&mapping->i_pages, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2740 | } else { |
| 2741 | ret = TestClearPageWriteback(page); |
| 2742 | } |
Johannes Weiner | 739f79f | 2017-08-18 15:15:48 -0700 | [diff] [blame] | 2743 | /* |
| 2744 | * NOTE: Page might be free now! Writeback doesn't hold a page |
| 2745 | * reference on its own, it relies on truncation to wait for |
| 2746 | * the clearing of PG_writeback. The below can only access |
| 2747 | * page state that is static across allocation cycles. |
| 2748 | */ |
Wu Fengguang | 99b12e3 | 2011-07-25 17:12:37 -0700 | [diff] [blame] | 2749 | if (ret) { |
Johannes Weiner | 739f79f | 2017-08-18 15:15:48 -0700 | [diff] [blame] | 2750 | dec_lruvec_state(lruvec, NR_WRITEBACK); |
Mel Gorman | 5a1c84b | 2016-07-28 15:47:31 -0700 | [diff] [blame] | 2751 | dec_zone_page_state(page, NR_ZONE_WRITE_PENDING); |
Mel Gorman | c4a2563 | 2016-07-28 15:46:23 -0700 | [diff] [blame] | 2752 | inc_node_page_state(page, NR_WRITTEN); |
Wu Fengguang | 99b12e3 | 2011-07-25 17:12:37 -0700 | [diff] [blame] | 2753 | } |
Johannes Weiner | 739f79f | 2017-08-18 15:15:48 -0700 | [diff] [blame] | 2754 | __unlock_page_memcg(memcg); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2755 | return ret; |
| 2756 | } |
| 2757 | |
Namjae Jeon | 1c8349a | 2014-05-12 08:12:25 -0400 | [diff] [blame] | 2758 | int __test_set_page_writeback(struct page *page, bool keep_write) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2759 | { |
| 2760 | struct address_space *mapping = page_mapping(page); |
Johannes Weiner | d7365e7 | 2014-10-29 14:50:48 -0700 | [diff] [blame] | 2761 | int ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2762 | |
Johannes Weiner | 62cccb8 | 2016-03-15 14:57:22 -0700 | [diff] [blame] | 2763 | lock_page_memcg(page); |
Huang Ying | 371a096 | 2016-10-07 16:59:30 -0700 | [diff] [blame] | 2764 | if (mapping && mapping_use_writeback_tags(mapping)) { |
Tejun Heo | 9101813 | 2015-05-22 17:13:39 -0400 | [diff] [blame] | 2765 | struct inode *inode = mapping->host; |
| 2766 | struct backing_dev_info *bdi = inode_to_bdi(inode); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2767 | unsigned long flags; |
| 2768 | |
Matthew Wilcox | b93b016 | 2018-04-10 16:36:56 -0700 | [diff] [blame] | 2769 | xa_lock_irqsave(&mapping->i_pages, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2770 | ret = TestSetPageWriteback(page); |
Peter Zijlstra | 69cb51d | 2007-10-16 23:25:48 -0700 | [diff] [blame] | 2771 | if (!ret) { |
Dave Chinner | 6c60d2b | 2016-07-26 15:21:50 -0700 | [diff] [blame] | 2772 | bool on_wblist; |
| 2773 | |
| 2774 | on_wblist = mapping_tagged(mapping, |
| 2775 | PAGECACHE_TAG_WRITEBACK); |
| 2776 | |
Matthew Wilcox | b93b016 | 2018-04-10 16:36:56 -0700 | [diff] [blame] | 2777 | radix_tree_tag_set(&mapping->i_pages, page_index(page), |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2778 | PAGECACHE_TAG_WRITEBACK); |
Miklos Szeredi | e4ad08f | 2008-04-30 00:54:37 -0700 | [diff] [blame] | 2779 | if (bdi_cap_account_writeback(bdi)) |
Nikolay Borisov | 3e8f399 | 2017-07-12 14:37:51 -0700 | [diff] [blame] | 2780 | inc_wb_stat(inode_to_wb(inode), WB_WRITEBACK); |
Dave Chinner | 6c60d2b | 2016-07-26 15:21:50 -0700 | [diff] [blame] | 2781 | |
| 2782 | /* |
| 2783 | * We can come through here when swapping anonymous |
| 2784 | * pages, so we don't necessarily have an inode to track |
| 2785 | * for sync. |
| 2786 | */ |
| 2787 | if (mapping->host && !on_wblist) |
| 2788 | sb_mark_inode_writeback(mapping->host); |
Peter Zijlstra | 69cb51d | 2007-10-16 23:25:48 -0700 | [diff] [blame] | 2789 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2790 | if (!PageDirty(page)) |
Matthew Wilcox | b93b016 | 2018-04-10 16:36:56 -0700 | [diff] [blame] | 2791 | radix_tree_tag_clear(&mapping->i_pages, page_index(page), |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2792 | PAGECACHE_TAG_DIRTY); |
Namjae Jeon | 1c8349a | 2014-05-12 08:12:25 -0400 | [diff] [blame] | 2793 | if (!keep_write) |
Matthew Wilcox | b93b016 | 2018-04-10 16:36:56 -0700 | [diff] [blame] | 2794 | radix_tree_tag_clear(&mapping->i_pages, page_index(page), |
Namjae Jeon | 1c8349a | 2014-05-12 08:12:25 -0400 | [diff] [blame] | 2795 | PAGECACHE_TAG_TOWRITE); |
Matthew Wilcox | b93b016 | 2018-04-10 16:36:56 -0700 | [diff] [blame] | 2796 | xa_unlock_irqrestore(&mapping->i_pages, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2797 | } else { |
| 2798 | ret = TestSetPageWriteback(page); |
| 2799 | } |
Johannes Weiner | 3a3c02e | 2014-10-29 14:50:46 -0700 | [diff] [blame] | 2800 | if (!ret) { |
Johannes Weiner | 00f3ca2 | 2017-07-06 15:40:52 -0700 | [diff] [blame] | 2801 | inc_lruvec_page_state(page, NR_WRITEBACK); |
Mel Gorman | 5a1c84b | 2016-07-28 15:47:31 -0700 | [diff] [blame] | 2802 | inc_zone_page_state(page, NR_ZONE_WRITE_PENDING); |
Johannes Weiner | 3a3c02e | 2014-10-29 14:50:46 -0700 | [diff] [blame] | 2803 | } |
Johannes Weiner | 62cccb8 | 2016-03-15 14:57:22 -0700 | [diff] [blame] | 2804 | unlock_page_memcg(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2805 | return ret; |
| 2806 | |
| 2807 | } |
Namjae Jeon | 1c8349a | 2014-05-12 08:12:25 -0400 | [diff] [blame] | 2808 | EXPORT_SYMBOL(__test_set_page_writeback); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2809 | |
| 2810 | /* |
Nick Piggin | 0012818 | 2007-10-16 01:24:40 -0700 | [diff] [blame] | 2811 | * Return true if any of the pages in the mapping are marked with the |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2812 | * passed tag. |
| 2813 | */ |
| 2814 | int mapping_tagged(struct address_space *mapping, int tag) |
| 2815 | { |
Matthew Wilcox | b93b016 | 2018-04-10 16:36:56 -0700 | [diff] [blame] | 2816 | return radix_tree_tagged(&mapping->i_pages, tag); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2817 | } |
| 2818 | EXPORT_SYMBOL(mapping_tagged); |
Darrick J. Wong | 1d1d1a7 | 2013-02-21 16:42:51 -0800 | [diff] [blame] | 2819 | |
| 2820 | /** |
| 2821 | * wait_for_stable_page() - wait for writeback to finish, if necessary. |
| 2822 | * @page: The page to wait on. |
| 2823 | * |
| 2824 | * This function determines if the given page is related to a backing device |
| 2825 | * that requires page contents to be held stable during writeback. If so, then |
| 2826 | * it will wait for any pending writeback to complete. |
| 2827 | */ |
| 2828 | void wait_for_stable_page(struct page *page) |
| 2829 | { |
Christoph Hellwig | de1414a | 2015-01-14 10:42:36 +0100 | [diff] [blame] | 2830 | if (bdi_cap_stable_pages_required(inode_to_bdi(page->mapping->host))) |
| 2831 | wait_on_page_writeback(page); |
Darrick J. Wong | 1d1d1a7 | 2013-02-21 16:42:51 -0800 | [diff] [blame] | 2832 | } |
| 2833 | EXPORT_SYMBOL_GPL(wait_for_stable_page); |